Don't know what title to put

So I am over 40 and its still a hard time talking about sex and all the feminine stuff. Like I think all of this stuff sex wise in my head but feel stupid when I talk about it, even to my boyfriend of 3 years. Like even during sex I get all in my head and be like oh what was that sound or I should do this tomorrow. Now don't get me wrong it feels good and all but my head goes somewhere else sometimes. During sex yea I'll make a few noises here and there but want to express more during but again it feels stupid coming out of my mouth. Why am I like this, it brings down my self-esteem and my confidence. Anyone have any ideas?