How can we fix our relationship?

So my ex and I dated for 4 years. In those 4 years, I broke up with him twice. Once in the end of the third year because I was going through a bad time in my life and I pushed him away, we got back together in a month. The second was at the end of the 4th year because I needed to focus on myself and needed the space of being alone. It has been about 6 months and I know I love him. I never stopped loving him, I just needed to be by myself because I was unsure of my relationship. We had been together since we were 17, and I did not know what it was like to be by myself. I know that I hurt him, twice. I know that it is my fault because I initiated the break up. Well recently I told him I was still in love with him and that I would like to start over. I poured my heart out to him and he said, he doesn’t know if we are compatible because we had already broken up twice. He asked for time to think it all over. Is there anything that I can do? Or say? How much space and time should I give him in waiting. I know that I broke up with him and therefore that, if he doesn’t come back, it was my doing. I just want some help, on how to help the situation or at least to have him make a decision.