Has your boyfriend been with other girls ? If so, 18 months is a long time without sex if you both would like that. From your description, he sounds hesitant to have full sex. So you need to find out why. Is it...
1. He doesnt believe in sex before marriage. Nothing wrong with that.
2. He is inexperienced and scared he cannot satisfy you. Then, you must encourage him more BUT do not pressure him into sex.
3. You have said something that has put him off. Again, be gentle and find out what you did wrong.
4. If you are both uncertain, find other couples, perhaps older, with regular sex lives and ask about their experiences and how they overcame barriers to sex at the beginning.
5. Is there a medical reason he may be unsure. Perhaps something with his body to make him self conscious like spots on his back or small penis size or impotence caused by something like drink. If so, he should see a Doctor for advice.
This is not really the place for detailed sexual descriptions. As others have said, its a matter of personal experience. Some girls say sex is great all the time. Which is nonsense. If its part of a loving relationship it will means so much more over time. Just take it slow and tell each other what you like and dont like before and after sex. Learn over time to have great sex and love each other more.