How to get over penis shock?! :/

Ok so my boyf and I have been going out for 10 months and it’s only in the past few months that I started exploring his penis and that area. It’s not that I was afraid to,I just want to make him feel uncomfortable or forced but when I asked him about it and his erections and what I make him feel down there,well ever since then his dick has become like my new favourite toy,I love how big and hard he feels even when I’m feeling him through thick jeans…I get this silent mini orgasm from it. I can’t get enough of it,I want to get more access to his penis and give him a handjob but where we get to hang out,anyone could walk into the bedroom or room at any moment so we can’t take his pants off. He unzipped his pants and worn baggy jeans to make it easier and I could slide my hand down his boxers when we’re lying side by side on his bed but the biggest problem is…I have extreme and loud reactions. I scream really easily…ESPECIALLY if I touch something squidgey or that moves suddenly (both traits of his dick) and I’ve also always hated the look of dicks,they freak me to see and I get turned off if I associate a hairy naked saggy penis (no offence males!!) with my boyfriend or the erection I feel!! There is no point in telling me not to do it because I really wanna or I’m gonna go mad but I just really needs tips or whatever because this is my first serious relationship and I’ve never gone further than French kissing and him groping my boobs through clothes a bit with another guy. I’m 17 by the way and he’s 16 soon and yes I do plan on having sex with him sometime. Please help!!