First time having sex on T: Need advice on lube, height difference, and new vulnerability

[E4t.y.o.u.al1ve]

Hello, I am new here. I am afab trans masculine and I've been on testosterone since 14 and I am now 18. I understand sex can be different due to my bodily changes on testosterone, especially due to vaginal thinning.

I have a cisgender boyfriend who I adore immensely. We are sexually active though only have really done hand stuff and very recently ventured to oral, mostly on me because hes more of a service top. The last time he was over he and I almost had sex, raw after he gave me oral. He was a bit awkward but ultimately he was entirely fine about it as long as I was as well. He checks in a lot which I appreciate so much due to past relationships.

He managed to get the tip in before everything hurt, which made sense. He is 6 "3' and 250 pounds, I only stand at about 5"2'-5"3' and 160 pounds, so when we tried missionary it was a bit awkward due to him being so tall. Though doggy style is what got him to be able to slide in a little, after using his fingers for a few minutes.

I ended up going out to grab water based lube. I feel a little stupid being 18 and not understanding how lube works. I know it helps things slide in easier but specifically how does it help? My boyfriend has foreskin and is a little girthy but not anything daunting.

For more context hes 6 inches. We're both virgins so we don't have any scares about STI and I'm on a 3 month depo shot so I'm not worried about condom-less contact. I also genuinely feel like raw the first time feels more intimate and bonding in a way most modern relationships feel like to us through our mutual friends.

Recently as well I cant figure it out at all. Is that I genuinely am not scared of the idea of sex as I used to be. In past relationships they were very coercive and it took me months to feel comfortable around my ex in 8th grade, and since then every relationship I'd have would be only 3 weeks to 3 months long.

My boyfriend and I have only been dating about 2 months, though we understand eachother on a higher point because we've been through a lot of the same troubles, and because it seems as if we have a red string of fate thing going on.

Throughout our whole lives we've both known people eachother knew and were in the same children's programs at the same point in time.

I never genuinely thought that I'd ever feel comfortable naked around anyone even in a nonsexual context, though recently we'll just lay together giving aftercare wearing nothing or just eachothers hoodies we trade and nothing under. He has been my first consensual sexual anything, and I am scared. Not of the sexual intimacy, but the fear of "what if?" this is only a fleeting connection that will leave me broken if we aren't end game. This is the first time I've ever felt completely understood, emotionally, physically and hobby wise since hes a film major and I am an animation major.