Ejaculation problems

Patient: When i have an erection and my girlfriend and i begin to do stuff i cant really feel it like her hand or mouth or today we had sex for the first time and i couldnt really feel what was happening and i find myself unable to ejaculate as a child i suffered hits to my groin and i fear theyve messed me up for good and we intend on having kids and i dont want it to seem like i dont enjoy it because i cant ejaculate, what could be wrong with me?