ttc problems..

My hubby and I have been ttc for about 4 years. I was diagnosed with mild pcos symptoms fall of 2014 and we started fertility help Jan 2016. Since all of my symptoms are now under control and my body is finally having normal cycles, my hubby doesn't understand how important the ovulation days are. He doesn't at all want to have sex unless it's on his time, when he wants to. I am currently in my ovulation time and we need to get busy. How can I make him understand ? I just feel alone and discouraged...