Orgasm virgin 😂

I’m 33 and a virgin still (by choice). This seems like a ridiculous question to ask but:

My boyfriend and I have been experimenting with him touching me, and everything is good with that, but I close off right before I orgasm. I don’t believe I’ve ever orgasmed before, and he keeps asking me why I don’t orgasm for him. He keeps reassuring me to relax and breathe and he takes things slow, but as I get closer, it’s like I reach a point where I just stop. I don’t know how to explain it, I guess the closest thing would be like being tickled and at a certain point you’re just done with it.

I want to orgasm with him, but I don’t know what is causing me to clam up right before I do. So two questions:

1. Any tips on getting my brain and body to relax for an orgasm and

2. How do I know when I have had an orgasm?

Thanks in advance for any advice. I feel like a super newb even though I’m in my thirties! 😂