It seems to me like as lot of your issues are just as emotional/mental as they are physical. You're so lucky to have someone you can be intimate with who actually cares about you! You boyfriend posted that you prefer his penis because it's more "natural"... this sounds like a mental preference to me. Honestly, if you guys started from one, very well lubed, finger and worked your way up from there, phallic penetration might be much more enjoyable and easier for you.

Where are you guys when you're trying to have sex? You should be somewhere where you both feel totally comfortable, and can relax. I know anytime I've been with guys in the past and they suggest we just go at it while other people at home, I would tense up.

But honestly, I think until you are comfortable touching your own body, you won't be able to let your boyfriend do it. There's no shame in exploring yourself. Babies touch their genitals, that's how normal and natural it is to explore yourself! Just lay down one night (with a mirror, if you can bear it) and just start small exploring yourself. Just relax and try to feel around noting what feels good and what doesn't. Don't be afraid of your vulva! It's obvious that your boyfriend likes it :c) Like everyone else said- You must be comfortable with yourself, and love yourself, before anyone else can.