is this good?

my start weight was 51kg
i was constantly throwing up and could hardly eat til week 17, i'm now 21 weeks and i've gained around 11lbs

It's perfectly normal. I am 33 weeks and have gained 13 pounds and the doctor said it's fine. You will gain generally 20-30 pounds over the course of your pregnancy, most of them during the last couple of months.

Quoting Tabatha Perkins Hunt:" It's perfectly normal. I am 33 weeks and have gained 13 pounds and the doctor said it's fine. You will ... [snip!] ... fine. You will gain generally 20-30 pounds over the course of your pregnancy, most of them during the last couple of months."

is it normal that i havent been weighed since 12 weeks? or am i supposed to be weighed regulary? stupid question maybe haha

I guess every doctor may be different, but mine weighs me every visit. If you're concerned, I would talk to your doctor. There is probably a reasonable explanation for only being weighed occassionally. I might be weighed every time because I'm high risk.