Due to repeated masturbation i found my dorsal vein size increased i think this is effecting my erections because blood doesn't flow to my pennis head?

Erection: The blood vessels responsible for erection are not visible normally. The veins you see are most likely superficial veins which doesn't have any role with erection. If in doubt, see a urologist.

Wouldn't matter: Use / non-use or self-abuse won't make structural changes to your penis. If having concerns about erections, should see a urologist for exam to be sure there is nothing wrong.