Your concern is understandable. You can not see sperms through naked eyes, though it is a normal finding in urine microscopic examination to have few sperms. It is the pre coital fluid / secretion which is passed with urine especially if you are pre-occupied with erotic / sexual thoughts.
There is nothing abnormal in masturbation
and in no way it is going to affect your married life. Rest assured.
I suggest you should not harbour any complex/ negative feelings regarding penis size. It is the upper 3rd of vagina which is most sensitive. There should not be any problem.
I thank you for submitting your question. I hope you find my response to be helpful and informative. If you have any additional concerns I would be happy to address them.
'Wish you Good Health'