I LIKE SOMEONE FOR ONCE - how do I approach them?

HELP! I am currently 19 years old and haven’t been interested in anyone properly since I was 16 but have now started working with this guy who I am really attracted to. I have incredibly low self-esteem and think that’s why I never let myself get close to anyone because I don’t want the rejection or inevitable break up to set me back further, I never let myself experience anything because I’m so scared of a negative outcome but it means I’ll never get a positive one either. I consider myself ugly, fat and overall very unattractive, and although this has technically be disproven by the fact people have been attracted to me and told me otherwise, I have found it so hard to love myself since I was raped and pick at every little flaw, so the thought of liking someone and them not liking me back and therefore confirming those flaws is terrifying hence why I never take things further with anyone. Although I am getting more and more confident and attempting to build myself up, I know how fragile I am. The guy I like is 27 and so I’m scared I’d be too young for him, we work together but it’s a temporary position and if nothing happens soon then chances are I will never see him again. I am stuck in the old fashioned way of thinking that in a male-female (which is typically dom-sub) relationship the male should make the first move, not necessarily because they have to but because if they were interested they would (and be dominant about it) and so I fear he doesn’t like me in the same way or he’d have done something about it, I’m terrified of making the first move and being rejected, especially because when girls do they are labelled ‘crazy and desperate’ and especially with the age difference, I would come across so naive. There have been a couple of moments where the two of us have been alone but been interrupted where I feel something could have happened, for instance there was mild hinting at going home together but then another girl was quite drunk and needed help home so when we walked that way we just ended up going our separate ways. What should I do? I really like him and ideally want something to happen but I don’t know how to go about this, I’ve always rejected guys in the past because of all my negative experiences but I only have positives to say about this guy so far. Nothing remotely has happened between us, there’s just chemistry and I wouldn’t want to lose out on my first feelings in three years. What should I do?