Only the head of your penis needs to be covered and you say you tested with a 4th generation Duo test at 4 days? Sounds like no risk to me (only risks are unprotected vaginal or anal sex or sharing IV drug needles to inject drugs) and you had a conclusive negative test (which wasn't needed as it was a non risk). So, no worries about hiv here. Use latex condoms in the future.
What kind of non-latex? Anyway your duo was conclusive so you are safe.