Help Trying to Conceive

My husband & I have been trying to get pregnant for a few years now with no luck until last July when we were blessed with twins. We were so excited & everything was great we did everything & anything to better ours & prepare for the arrival of our babies. But when I was at 13 weeks I miscarried without any warrings. My doctor couldn't even explain what happened especailly since I had just had a great check up 12 hours previously to the miscarriage. So after that my husband & I decided that we didn't want to give up on our dream so we have been trying since the beingging of this year to get pregnant again with no luck. Is there any advise that anyone has for us to maybe help conceive?

Thanks
Ladi Frost