Boy probs.. help!

I dated my ex(Michael) for 4 years, we ended things in november. A couple of weeks later, I met a great guy(Caleb) that had also just gotten out of a 4 year relationship.. Caleb and I have been hanging out and seeing each other ever since that night. We just said that we would take things slow, have fun, and just enjoy each other without having to rush and put a label on it. Which I am cool with. He's a really really great guy, but the problem is my feelings for him always change. I never know what I am feeling.. sometimes I feel like I'm falling in love and he might be "the one", other times I feel nothing and just want to be with my friends.. Or I feel like this is good, but it's not gonna last.. I don't know how to have this conversation because i don't know what I really want with him and he has said he has feelings for me already just not the big "I love you". And I don't want to stop seeing him right now.. shouldn't i know exactly what I feel by now?