I feel people are missing a key detail. "She said she didn't want to because she is not getting anything out of it." Sounds like to me she isn't enjoying the sex. It may seem like a chore to her so ask her why she feels that way. Maybe you don't last long or too long. Maybe she isn't climaxing, if she isn't climaxing try foreplay before going into intercourse. Remember sex is a co-op event that both parties deserve to enjoy not just you or her.

The no masturbation rule has got to go. It doesn't matter how insecure her feelings are, you deserve at the very least to relieve yourself. You guys had a deal and now she wants to change it in her benefit. If none of this work and she continues to not properly communicate about the problem, I'd move on personally. Sex is important for me and I myself have a high sex drive, but my GF has not a great past so she has a pass and were making progress which all I care about. Her being able to move on from it is the goal. Sex will come later.