How soon before a missed period can a test show up positive?

Im not to good at the whole so many DPO thing, so just in days before a missed period, what is the average a test would show up positive?? I know every woman and pregnancy is different, so like i said, on average?

My reason asking. I just found out that I m pregnant after a long trip the ER last night, they told me my hcg levels are around 2000.
I just had a period on september 18th, which was completely normal and just on time. So that would only put me at around 2.2 weeks.... well i decided for the heck of it even though i was told in the ER that i am pregnant, to take a HPT, and it came out clear as day, a BFP. So my question is, If I really am only 2.2 weeks, would it be possible that this test came out a clear positive? is it possible im further along?
they did an internal and external u/s and couldnt see anything.

sorry the pic is blurry, but its clearly noticable theres a bright line there.

Some tests can tell sooner than others example would be the first response which can tell you up to 6 days before your missed period hospitals can also test your blood to tell hope this info was helpful  

Ether that wasn't really your period or you definitely didn't ovulate two weeks after getting your period. I could be crazy and remembering everything all wrong, but you should have only ovulated a few days ago if you have a normal cycle. I think you're probably farther along than you think you are or you ovulated a lot earlier.

I did a test that tested as early as 5 days before the 1st day of your next expected period and had a very clear positive so tried a simple test and got the same result  
Bloods os most accurate  

Quoting Theresa Vaandering:" Some tests can tell sooner than others example would be the first response which can tell you up to 6 ... [snip!] ... can tell you up to 6 days before your missed period hospitals can also test your blood to tell hope this info was helpful  "

well this test i used is just a strip, not sure the brand, i ordered them off amazon and got 10 for 4 dollars.
and yes at the hospital they did a blood test which is how i found out, and said being i just had a period and my hcg levels were only 2000 im about 2.2 weeks along, but im not due for my AF till about the 18th or so of this month, and this HPT i took came out clear as day a BFP.

Quoting Mama to William + 1:" Ether that wasn't really your period or you definitely didn't ovulate two weeks after getting your period. ... [snip!] ... ago if you have a normal cycle. I think you're probably farther along than you think you are or you ovulated a lot earlier."

Agree. Although it's possible OP ovulated right after AF, who knows?

Quoting Mama to William + 1:" Ether that wasn't really your period or you definitely didn't ovulate two weeks after getting your period. ... [snip!] ... ago if you have a normal cycle. I think you're probably farther along than you think you are or you ovulated a lot earlier."

No, i dont think your crazy, i just dont know how all this is happening and possible. the AF i had last was just right on time and normal, but i dont see how this test showed up so good, but yet the ER doctors told me my hcg levels were around 2000 and im bout 2 weeks along

Quoting BaileysMum:" I did a test that tested as early as 5 days before the 1st day of your next expected period and had a very clear positive so tried a simple test and got the same result   Bloods os most accurate  "

that seems about what ive heard, but im more then 5 days before. i shouldnt have my next one till the 18 or 19th....

Quoting Cat Abbott:" Agree. Although it's possible OP ovulated right after AF, who knows?"

I wish i knew. this is all so weird and confuseing to me.

I found out at 2w6d (ovulated day 11 tested day 8-9DPO. Got a faint at 8 and a real positive at 9dpo).

I went in for a blood test at my docs office at 3w1d and had a level of 23.

You either ovulated CRAZY early or you didn't have a real period and your implantation bleeding was just LIKE a period.

An ultrasound will possibly tell you which it was. I wouldn't worry too much about it til then.

ETA---my period want due for 10-11 days when I got my BFP on a cheaply test (and a FRER with same pee)

Quoting P Pickle Pants:" I found out at 2w6d (ovulated day 11 tested day 8-9DPO. Got a faint at 8 and a real positive at 9dpo). ... [snip!] ... much about it til then. ETA---my period want due for 10-11 days when I got my BFP on a cheaply test (and a FRER with same pee)"

hmm, i wish i knew when i ovulated and all that. its very weird to be going through this, just about everyone is saying levels of 2000 seem high to be only 2 weeks or so, but i have no idea. i go for blood work tomorrow to check my hcg levels to make sure they are going up like normal, if not then they said they believe it may be an ectopic pregnancy. i hope not. its kind of a blessing for me to get pregnant so fast only the 3rd month after being off the pill. I didnt think it would happen so soon and yet it had and things are already starting off bad

Quoting adяiyanas mami:" No, i dont think your crazy, i just dont know how all this is happening and possible. the AF i had ... [snip!] ... see how this test showed up so good, but yet the ER doctors told me my hcg levels were around 2000 and im bout 2 weeks along"

Well, I found out I was pregnant at 7 1/2 weeks with DS. I had what I thought was a lighter period (I was on the pill so that was normal) and didn't get a positive at 4 weeks or 5 weeks so I thought I was good.

Quoting Mama to William + 1:" Well, I found out I was pregnant at 7 1/2 weeks with DS. I had what I thought was a lighter period (I ... [snip!] ... lighter period (I was on the pill so that was normal) and didn't get a positive at 4 weeks or 5 weeks so I thought I was good."

hmm, yea because i tested last month on the 17th and it was a BFN, and then AF came on the 18th. and was normal. its just so weird

I had pink/brown bleeding on the 12 if march I didn't get a positive test till the 12 th of April. My due date is the 23rd of Dec. Am the same as u it just doesn't add up.