WarpMyMind

I'm looking for a silent subliminal for my girlfriend to become a slut for me and change her body as well. Ideally slimming down while fat is directed to breasts and butt. Is there anything like this?

Silent subliminals don't work.

Let's see... #1 Jackstock is right.
#2 even if he was wrong and I sold you one(custom work runs $175) I would still warn you that hypnosis only works on a willing mind, so you'd better hope she's willing. and that getting her to exercise may work but we can't guarantee where the fat might redistribute although we can try.
#3 what your trying to do MAY be illegal where you live
#4 if she finds out somehow you are VERY likely to end up with an ex girlfriend, legal trouble, or both.
#5 you're MUCH more likely to get her to be a slut for you by spending time encouraging the behaviors you like, and rewarding her for doing them, making being your slut something special to her rather than something a random stranger on the internet attempted to impose on her(and yes this does mean paying attention to her sexual needs, not just your own).

Anyway, good luck, there's probably a couple subliminals on the site that will match your needs, just don't expect much.