Ugh I feel really embarrassed and annoyed?

So I am 14 (just turned 14) and own one cup bra, size A32. I usually still wear the colorful sports/training bras for 5th graders. So my best friend is also in my grade, but she is a year younger than me, just turned 13. She is COMPLETELY flat chested, and doesn't wear a bra, just undershirts. I feel really akward and like my boobs are huge when I am with her, mostly when we change for gym (I always wear cami undershirts changing but still feel like my boobs are noticeable.) I hate having boobs at all, they just get annoying and I wish I were flat chested still too, I went from flat chested to A pretty much this year. I want to make my boobs less noticeable, I want to look 12 or 13 , younger, I feel so OLD with my bff, it doesn't help that i'm like 4 inches taller than her either. Advice please? Also, summer is on it's way and the only bathingsuits I have are ones without bras, my mum even just bought me a new one, but it has support for my chest (even though it's small my chest is existant), I am way to embarrassed to mention it to my mum, she asked me if it had support when she brought it home for me to try on, I said no,she didnt respond , and didnt comment when i tried it on. What should I do about the bathingsuit?