I will talk to you about Abstinence with a different viewpoint if I can.
Think of Abstinence as less of some pledge you make which you must achieve but more of a standard kept until you achieve what marriage stands for: true love. I know you are probably just a teenager so you most likely will believe many relationships were "The one" etc. etc. but you truly need to evaluate what abstinence could be all about: devotion.
I will be the first to admit: I am a virgin. I have been on-and-off dating with my girlfriend for the past 3 years. I (in a teenagers belief anyways) love her to death. She wants to have sex. But I am simply not ready to make that step. That's fine. She is understanding of that. You really need to work on the emotional aspects of the relationship, that way as your love for one another reaches new heights; you're physical actions will just occur naturally.
Forget about the STD's, pregnancy, etc. That shouldn't be your motivation. A strong moral compass will get you much farther than skewed statisitics using insane conditions. You wan't to date a girl or guy who you find things in common with who you also feel at least somewhat attracted towards. Enjoy activities with each other. Rely on each other with any and all emotional problems you have and help each other. If her mother isn't treating her well, lend her your shoulder to cry on. You both should be 2 seperate, independent, entities which make each others lives just a little bit easier.
In short, have sex with a person who you have grown a deep relationship with when you and your partner are 100% ready. If you and your partner get to that point, and are completely faithful, then simply by practicing safe sex your odds of acquiring an STD are slim to none.