I been trying to have a baby with my girlfriend but have small testicles and i don't get a hard on all the time and i feel horny but don't get excited?

Anxiety, Depression: I understand your concerns. You are a good human being with abilities and skills. Stand in front of the mirror and say that you believe in yourself and that you respect yourself. Do not focus on size of testicles and erection problem. Have heart to heart talk with your girlfriend to develop Emotional, Physical and Sexual Intimacy. Use Breathing and Music Relaxation. See a Therapist for stress.

A urologist or: your family doc is they person to see. He/she can measure your hormones, check for other things that may be an issue, and help. Peace and good health.