Question about uterus measures

ok so when i went to the doctor at 15 weeks and 6 days my uterus was measuring 20 centimeters ans when i went again at 18 weeks and 5 days i was measuring 20 cen. still so im just wondering what is that about because i was reading that you should measure around the same cen. as how many weeks you are i understand it can be off a little but thats a little far off and the whole thing is confusing anyway because i missed my period in january i took a pregnancy test on feb.1st to be exact than feb.4th i woke up and i was bleeding and so i fugured that ok im not pregnant i got my period but when i went to the doctor they said they preg. test cam back positive so i was confused about everything and the nurse told me to go to the er so i went and they told me i had an abortion but march i missed my period again i took a preg test it came back positive and when i got my sonogram on april 18th (went to the er cause i was spotting) i was 9 weeks and 2 days and my doctor was like she doent know how i was so far and had a miscarriage because according to my doctors i got pregnant in the beginning of feb. im going to get a sonogram thursday i wonder if they change how far along i am but just tell me your opinions please im so sorry i wrote so much just didnt want you to be confused

Whoa... That's the longest run-on sentence I've ever seen in my life..

I don't know what to tell you..

ha i barley use periods either but im 38 weeks and measureing 41 cm so idk

You will start measuring your week at 20 wks usually. Thats why most docs dont start that measuring until 20. Or you will be 2 cm off of your week and thats normal too.

Yeah... I couldn't even read that, sorry.