I am shy about things I want to do. How do I become comfortable with myself?

Background : I am a 27 yr old male. I have sex with my girlfriend a lot and I love it. Our sex lives One of those is that I want her to dominate me with a strap on. A few weeks ago she was going down on my and gave me a rim job. it was amazing. I asked her to put in a finger and she did. Again this was an amazing intense feeling, she even pushed on my prostate. We came to realize after that I was bleeding, yes from down there. It turns out that her finger nails had cut me. After doing some research we were not worried. The thing is that we have not done that since but we have had sex multiple times since. I was shy before and now I am extremely shy and embarrassed from this incident. I also feel like I am not comfortable enough with my sexuality and self esteem to ask her to take it to the next step. I know she will but I just feel so vulnerable. Any advice?