Rough(ish) sex

My husband broke his back in 2013, and us not being in the gym for the past year has taken a toll on him, along with working. So, 95% of the time I'm on top (reverse cowgirl to be specific). We never have slow sex (even though I miss it), I usually have to be like a rabbit so he can finish. I'm just wondering if this is dangerous for the baby? Or what an alternative is for us. I'll be 15 weeks tomorrow, & I have no medical restrictions. I'm just trying to be precautious. What are your thoughts?