Sexual confidence advise?

So my boyfriend came over recently, I’m 21 he’s 22, and things got steamy but I’m on my period. He said he didn’t mind but I kinda did because I didn’t want to get my bed dirty and idk I get embarrassed easily even though I know I shouldn’t I just can’t help it. We’ve had sex before, not a lot but a couple times. Then he said we could do other things. He said (in a totally bit rude way) he’s gone down on me maybe I could try it and I got so embarrassed! My face turned beet red and was super hot I couldn’t even speak. I don’t want to be embarrassed or shy around him but I’ve always been this way when it come to sex and stuff like that. What can I do to be more confident about that kind of stuff?