I need help! (Bra stuff)

I need to go shopping for bras and underwear since my newest bra is like 6 months old but I can’t find my size anywhere! I’m a 32DD and whenever my grandma takes me shopping (because I spend most of my time at her house) she always picks out the cheapest stuff that you can tell is going to fall apart after one wear and she doesn’t believe me when I tell her my size and I don’t trust online shopping.

I live with my dad mostly because he only lets me see my mom once a week which is completely unreasonable so she can’t take me and I don’t want to ask my dad to take me because I want to get some cute stuff. I’m not allowed at my local mall alone either because I did something dumb so idk what to do!