Frustration

My husband and I have been married for 4 years and I have children from my first marriage. Back in September we decided that I would undergo surgery and have my tubes untied so we could have a baby together. The problem is after spending most of our savings on the surgery, it takes a miracle to get him in the mood and I am lucky to BD once a week. He works out of state and is home only on weekends and when he is home he doesn't seem interested. He accuses me of using him for sex because all I want is a baby.  Oh and to top it off he has been diagnosed with low T. Any advice?