Husband wont have sex

Hello! I am in situation and I need some help.. My husband and I have been married for 6 months, but have been together for 4 years. In the first 5 months of our relationship we had sex every day or every other day and then we bought a house together and he slowed way down almost overnight. We usually will have sex once every month or every other month. On a good month we will have sex 2 times. When we do have sex he wakes me up from a dead sleep at 3 or 4 am and we do it then. I have tried EVERYTHING to get him into the mood and it never works. He is unwilling to use toys. I have tried to give him a BJ while he was playing video games or spontaneously disrobing in front of him.. I have sent him random sexy pictures, etc. And they all fail. He always uses the excuses "the kids arent asleep yet (his kids from a previous marriage 11 and 12 yrs)" - "im too tired" - "my stomach hurts"-" I have a headache" - "im too old" and "im too fat". (hes 31 and 190 lbs) I have offered to do all of the work, and he still says no. I have had thoughts that maybe his testosterone is low, but he refuses to see a doctor. I cant help but take it personally, but he assures me that its not me. Any advice?? Help.