Hi, I want to assure you, masturbation itself will not cause any reduction in sperm count and infertility. I can understand that you are worrying about your potency, because even after several attempts of unprotected intercourse your girlfriend didn t become pregnant. If i had a patient with similar situation i would suggest the following probable options or reasons for intercourse which did not leads to pregnancy. 1. The fertile period for a girl is usually between 12-16th days of her menstrual cycle.Probably you could have had sex with her during the non fertile period 2.Few of your girlfriend s themselves may have some difficulty in formation of ovam which is necessary for union of your sperm to become pregnant 3. Finally i suggest you to check your sperm analysis after consulting a gynecologist or Urologist. They will look for your sperm count, motility of your sperm and few others. You should have at least 40 million sperms and 40% motility to make pregnant. There are several options available in this advanced scientific era, and hope you will find a solution based on these options.