My name is James, and i am 16 years old, i have a very active sex life and ever since i first had sex ive seemed to have the same problem. Before intercourse i may start to have an erection, and then it will continue for up to about 10 minutes while having sex, and then i realise i will have lost it, or it has deflated significantly. I'm worried i may have some sort of erectile disfunction, However i think it may be, that i have a short concentration span, or that i am thinking too much about it, and therefore losing it, can anyone give me some advice?