You're only young and with it being your first time you were probably just a little overwhelmed by the experience. Don't panic. The more you worry about this the more likely it is that it will happen again. Next time just make sure you are totally relaxed, take things nice and slow only moving from one step to another when you feel most comfortable. Why not take control. Instigate the kissing and then when you do have sex try being ontop so that you are totally in control of what happens. ALWAYS use protection and remember to never be pushed into sex, make sure that you are ready and feel confident, relaxed and comfortable with your partner. I'm 21 years old and I've been with my partner for 5 years. Sex is a very intimate part of any relationship and I'm sure you'll e happy to hear that I still find myself shaking afterwards on occasion, I don't know why but at least you know now that you're not alone. xx