i'm small :-.)

First off, for the umpteenth time, the size of a cock is only important to the limit that it can be inserted in a vagina and produce a next generation of human beings. That said, there are options to provide more pleasure in that department.

One way is to use a vibrator as a mutual sexual toy. You can enjoy fucking her with the vibrator (or static dildo) until she is on the verge then push inside her and finish the job. Perhaps being stimulated to that point may help her to enjoy what you offer to more effect. Another possibility is to fuck her till she orgasms then push into her and use the warm wetness of her post orgasmic vagina to stimulate you to your orgasm. I always get super turned on when my mate cums before me and it usually gets me off pretty quickly thereafter.

Another thing I have seen is a prosthesis you can wear over your penis which stimulates you and gives her a larger member to fill her needs. I have never tried this but it seems like it could be enjoyable for both. Sort of like using a strap-on.

As a last comment, presuming that you mean you have fathered two children with your wife, you have obviously been successful at having sex together. This sounds like it isn't a problem that is either one of yours alone but is something that you both need to address and find a pleasurable solution for. I wish you good luck. It sounds like it could be a fun problem to have.