Scared of foreplay

My boyfriend and I have been dating for a few months now and we're both virgins but we both agree we're ready for sex. I have blown him and he has fingered me but that's all. He has expressed an interest in going down on me but I'm scared. He tries puppy dog eyes when he asks but I keep saying no. I'm sure it will feel good but I don't know WHY I'm scared of it. Should I wait until I'm ready or should I get over my fear now and let myself enjoy it?