Let me get this straight...
1) You have been going out with this girl for ONLY 4 1/2 months (on and off). Or does the on and off add up to more time? How long have you known eachother?
2) She has hook up friends... does this mean she had then while the two of you were together? If she had them, does that mean that she doesnt really care much about sensuality, it's just a way to pass the time? because if you think about it, it sounds like she just did it to do it. and now that she has you, she feels secure and not required to do anything. ... and with the kissing thing, it isnt a big deal. I have told my boyfriend that i didnt like the way he kissed, but it may be just the lack of experience or your too fast or too "hungry" that takes all the emotion out of it. You have to realize that kissing is an emotional expression that is sooo underated in out time and age. It is what leads to running the bases. You have to really understand that "moving on" if its meant to happen, it will just happen. But how much farther do you really want to go? Especially, think about what the most responsible thing to do would be. If you both want to mess around, i dont think you really have to talk about it, it will happen. and if she doesnt want to then she'll make you stop unless she feels like you are going to reject her for it... which you are NOT right? You can't judge a person on the way they kiss or what not... you just have to feel the connection (not body to body) but more like soul to soul. If you can read her eyes and know that she loves you, what else matter. And you may just be moving too fast... i mean 4 months? Well... it is the 21st century, but i still think its too fast.
Plus you may just "think" you want to move farther because your thinking with your hormones and not with your BRAIN!
Hope this helps, if not ... sorry. I just thought you would appreciate my point of view.