I don't know what to do, please help!

Okay so i met this girl and we have been dating for about a month now. I'm 16 (almost 17) and she's 18. I think i love her and she's says she feels the same, but she has this ex who she was with for more than a year and who she did stuff with (gave him head, and got fingered) and he is two years older than her; now she tells me that she regretted doing stuff with him and never wants to do them again...and said she could only go to second base with me; and i think i really love her and don't want to cheat on her...but the hormones and all, like i want to go past second base with a girl...and now i'm saying she prefers him to me cause she would go further with him, and its led to an argument

Uh, nah, she's probably just regretting letting someone she didn't love take some of her purity.
She says she loves you, but she isn't sure. She wants to take it slow to make sure you aren't stringing her along and such just to get some. She'll come around, but you definitely have to give her time: it's only been a month.
You have the internet. Watch porn.

Thanks but she says she loved him, i think she's sure of her feelings for me as well. I don't think she's just taking it slow because she says she never wants to do those things again and she hated herself for it. I haven't explicitly told her I want to because she would get upset and feel like i don't love her. Its harder for me to resist the temptation of doing things with other girls as they are things my girlfriend isn't offering

Maybe tell her that...?
See what she's comfortable with insofar as solving that problem?

Leave her alone, break up with her and go experiment with your hormones with someone who is actually ready and willing to be with you sexually.

You're too young to be in a committed relationship with an 18 year old that is afraid of sex anyway. Wear a rubber every time you have sex and NEVER leave your chances of not getting someone pregnant up to the girl. Where a rubber until you are truly committed and are financial and emotionally mature enough to take care of yourself, your WIFE and your baby. That means wearing rubber even if she tells you she's on birth control until you have a full time career and a ring on her finger.