Embarrassed to go bra shopping?!? help.?

I'm 13, turning 14 years old pretty soon, like within a week, but anyways, I really like wearing lightly lined bras, and i think they're so comfortable. I only have one pair though, and I would like to get more. I'm really embarrass to go bra shopping with my mommy, and I want to get my bras at La senza, but, would it be awkward if I went and got my bras there? I'm like, 32A or 34A ,my boobs are small... will they have my size??? ... Cause, I'm tired of gettting my bras at sears. .. lolol. I'm always scared to enter lingire stores like La Senza, and think they're embarrassing ..