MrBigD89, welcome to Psych Central! I've never heard of a "too big" penis. As you can imagine, most men wish they were bigger.

Perhaps if you tell the woman you are big before you get down to business, then that will help. Also, reminding them that not all of it will go in--and that if a woman can stretch to push a baby out, well....

Just lots of foreplay and maybe go slowly to start with.