Sex is perfectly okay up until your water breaks or unless your doctor says you can't for certain reasons. Spotting a little after sex is also normal. Hope that helps!
The baby's good, and since your doctor hasn't said no sex then you should be OK but you just might have to try different positions to find a comfortable one.
It's perfectly safe, baby is very well protected. Some people find it painful, you just need to try out a couple of positions and see which is best for you :)