How to get relationship back to normal

Okay so my boyfriend of 2 years broke up with me because he felt to much pressure so young and wasn't ready for a full blown commitment. We go to College together and are on the same cross country/track team in college. The break up was really hard we both had random flings with other people but then he would always call me back in to the picture and say "Your are the love of my life, but I just need more time". So about 8 months of being broken up we go back together and it was Amazing to be back with the person I love most. But now are relationship is very odd, and not quite the way it used to be. He is now completely hot and cold. Sometimes he doesn't act very "couply" to me in public and in front of the team he is cold to me. where as other days he is super flirty and nice to me in public. I am super insecure about the relationship because of our past and I could be overexerting but he sometimes just seems ashamed. When I asked him hat was up he said he loved me so much and that this time it forever and that I should Relax, I have no hing to worry about. Also, since we have gotten back together we don't have as much sex as we did be for (or when we were broken up). I always am the One start it whereas he used to get hard simply flirting with me. He always says "lets make our dinner date on Friday special No sex until then" he seems to have no urge in the in between days to break the rule. Next week is finals week so maybe he is Just stressed about school and the end of the track season. But I need advice on how to not to be so insecure and what I should do to peak his interest and get things back to normal. I dont want to break up again!