Perfectly safe, in fact it's good to have sex. It's a good workout for the muscles used durring labor. The more sex you have the easier labor will be.

Sex is perfectly safe. You will know if something is wrong and don't push yourself to do things if it hurts.

I can totally relate to you! I'm also 13 weeks and due to two previous miscarriages I've been terrified of having sex! I know in my head that my doctor said everything is great and sex won't hurt the baby but my main fear is that it'll cause some spotting or cramping and I know that would freak me out!

My first trimester I had no drive at all and when I gave in to my hubby (his drive only increased when he found out we were pregnant) it was uncomfortable no matter what the position, didn't feel good and I felt crampy and icky after (not bad cramps no bleeding) finally I said no more. Around week 12-13 I suddenly started having a drive again but with how bad it felt before I was a little reluctant. I was pleasantly surprised to find that when I did not only did I not feel icky, it felt really good and nothing bothered me afterwards. 

Sex is healthy throughout pregnancy. My doctorrecommends it actually, so my SO and I are pretty active. I'd say if you feel ready go for it... I'm sure your guy will be excited 😉

Yes unless you are told not by your dr then you are all good to go!