Size is a problem!!

My husband & I have been together for 5 years. He is very well endowed 10" long and very wide. After every sex session, however gentle we are, and however much lubrication we use, I get cycstitis, or reddening and soreness. It takes me days to recover and then it happens all over again. I have been checked out many times by my Dr, and there is nothing wrong with me! we have been trying for a baby for the last 8 months, but no success so far, probably due to the frequency we are able to have sex!! I am 34 now and this is making our lives miserable.