Wanting to, but waiting

My boyfriend and I have been going out for about 5 months now, and I really feel as though I love him deeply.
About a month ago I was at a party and I was talking to one of my friends, who asked me about sex and if I'd spoken to my boyfriend about it.
Because we hadn't spoken about it at all I thought that now was the time to. So we spoke about it, discovering that we both felt we were ready, but we probably wouldn't (both being virgins). The following day we were home alone and started kissing, which lead to this feeling that I can't explain but I was shaking and I could feel he was too. We started leading each other upstairs and onto the bed in the spare room with this kind of urgency, until I got freaked out all of a sudden. I love him totally but I feel as though it's only acceptable for us to have sex if we have been together for a lengthy period of time. My sister and her boyfriend who have now been together for something like 9 months had unprotected sex (her first time..not his) after going out for 2 months, which dissapointed my parents greatly.
I think that maybe I am scared that something will happen and I'll have to tell them, and that they will be disappointed in me too (the 17 year old younger sister).
Is it normal to feel like this?