For those of you who don't have kids or Can't have kids what do you fill your life with instead?

I have a 13 year old son and tried everything but cannot get pregnant again. I am only 32 and all me and my husband want is a baby but I just dont' think it will ever happen. My son is from a previous husband so my husband of now has no children of his own. After 3 years of trying and yes we have had all tests done nothing medically wrong with us. Cant afford IVF, I think we will have to accept we won't be parents again. I love my son to pieces and dote on him but I always thought i would have more, he is so independant now and barely in the house, I feel old before my time as i now can only look forward to my grand kids!!! (which realistically could only be 5 or 6 years away! lol) Me and my husband work full time, we socialise and have keen hobbies, he loves rock climbing and I am a runner, but I still feel like something is missing.