Nervous about sex

My SO and I met and started dating a few days before he left to go back to the military for a few months. It sounds rushed but it was just one of those insanely perfect connections. We're so happy together, even through the distance. Having sex with him before he left felt completely right so I didn't second guess it. When we did it though, he made me bleed and I'm definitely not a virgin so I'm not sure why exactly it happened. He's coming back home soon and I'm worried it'll happen again and make his time back home uncomfortable (for the both of us actually). Also, I'm really self-conscious about riding on top and feeling like I'm not doing it right. I just need pointers all around here😥😥 #desperateforhelp