How can i make myself last longer?

my girlfriend wants to have sex but im scared that im too small im maybe 5 inches

and everytime i beat off i can only last for about 30 sec how can i help that

Well, it ALL depends on wheather YOU want to have sex with your girlfriend. If your not ready to and your girlfriend just wants to, but you don't, then don't even have sex with her. And it also depends on if you love her. And if she loves you.
You need to think about it more.
And think about if you're even ready.
And think about wheather you TRULY love her. Don't mistake love with lust. As many teenagers do.
AND if she TRULY loves YOU then your size won't matter AT ALL.
It sound like to me, you need to think about it a little bit more.
I hope I helped you.

Dear yungguy09,
Size isn't important but technique is...so this is were your concerns should lie. If you are ready for sex then you and your girl friend should be able to talk openly and honestly about this. If you can't then you both are not ready for this next step. A first sexual experience can be disappointing when the couple isn't ready. Knowledge is power so both of you need to sit and talk about what to expect and do some research together. If you can't do this you are surely not ready.
Sue...good luck

Sue90 is right. You must be able to be open with each other on all parts of sex.