No sex for 10 weeks ?

Basically since week 3 we have been told not to have sex due to a threaten misscarrige He said we should be ok now- (I'm 11 weeks) but we decided to wait till the 2nd trimester incase. So I wouldn't of had sex for 10 weeks. I usually find the beginning of sex painful when he goes in because his so big, now I'm worried that it will hurt even more when we start again and cause bleeding. What's you experience/knowledge of this? Also going by my ultrasound I'm 11 weeks wheb will I be in the 2nd trimester!? Thanks :)