I really don’t know my breast size (plus I am so insecure about it)

I’ve got bras (of the same brand) that are 32A, 32B and 34B. 32A is small and exactly on me, 32B is not filled in the outer sides and is a bit tight all around, and 34B is ok but it is not filled on the top part. Also, my breast is so small so I can’t understand how come I wear a B cup. I am so confused.

Everybody makes me uncomfortable about my breast size also. For example if I like one top which is very V they (mother, father and best friend) all will say the same thing: “you won’t like the fact that it will be very V” or “Will it suit you well?” or even “that’s for bigger breasts”. Please help me find my size, I really hope I become a solid B someday, but As are too small so I don’t know. Maybe I am an alien. (I am 17 and got my period at 15 so I don’t know... maybe I am a late bloomer. My sister is 13 and got her period at 12, she has got breasts that look like mine and is always complemented. We freaking have the same boobs, why do they say that mine are no good and that hers are good? Maybe because she has got them at a younger age? Anyway, that is not the problem.)