If the head of your penis was always covered, you can't get gonorrhea, chlamydia, HIV, NGU or trich.
You could get syphilis, herpes or HPV, as those are spread by direct genital skin to skin contact, but I wouldn't worry a lot about that. Syphilis is uncommon, and your chances of getting herpes from a one-time, mostly protected encounter are low.
Have you been vaccinated for HPV? If you haven't, talk to your doctor about it.