I'm having trouble finding a bra that works for me?

I'm 21 years old, on a tight budget. I have a weird build so it's hard to find clothes in general, but mostly with bras. I'm a petite girl, but I'm busty, and depending on what brand/style the bra is I can usually deal with about a 36 DD, but usually it's still not a good fit...The bra rides up too high in back because of the weight in front, my look lumpy because of the padding and my s pop out weird on top..And I can NEVER go without those things that hold your bra straps together in a racer-back style. Again I'm on a tight budget so places like Victorias Secret are not really an option. Basically bra shopping is a pain in the back (haha) and I'm just wondering if anyone has any non-expensive brands or stores that I may can find something that works. Or just bra shopping tips in general! Thanks in advance!