In 3rd year and don't know anyone

First year was online so I lived off-campus, then I took a year out, then my second year was a year abroad. So I've just started 3rd year and I don't know anyone. I met 1 girl from my university on the year abroad who kindly invited me to join her houseshare with 5 others, but I've been here for a week and it's been hell so far. I hear them in the hallway all the time chatting and laughing and I don't want to intrude because I'm literally a stranger living in this house full of friends so I've just been hiding. Too scared to leave my room to even use the toilet, let alone make food. I'm only brave enough to leave my room once a day- shower, pee, and run to the local sainsburys to grab a meal deal. Been surviving off 1 meal per day. Been here for a week, still don't know what any of my roommates even look like. They probably (obviously) think I'm weird. After covid ruined the first half of my uni experience I was determined to have a normal one for the second half but my anxiety is ruining it for me. Classes start on Monday but I know for sure I'll be ignored since everyone's already made their friends literally 2 years ago and I'm too anxious of a person to initiate things. The typical 'don't worry, everyone's in the same boat as you/just as nervous as you are' advice that is given to freshers (which is pretty much what I am) obviously doesn't apply to me or help, so hearing it makes me feel so much worse. Using that 1 girl I already know as a way to meet/be introduced to more people would be the logical course of action but she hasn't spoken a word to me since we came back from the year abroad so we're not exactly friends in the first place. Any advice for me?

How do I do that? I feel like I've already barged in on them and their lives by entering & living in their house. What do I do, just waltz into the kitchen and ambush them? Hey guys, you don't want me to be here because I'm literally a stranger but hi!!! Hang out with me NOW!!!!!!! They're like 2-3 years younger than me too. I'd be scared if I were them.

Lol that's nothing. Literally siblings ages. Don't let that cloud you.

And its a house-share - not a home. You aren't intruding if you are paying rent and were invited to live there. Do you think she invited you to fill a space? If so that's a cause for concern but if you haven't even started talking with them how will this get better? You can be honest and say why you were kinda avoiding them but you dont even need to do that considering its only been a week. Could just say you were settling in. Just start of simple see where it goes! You can't let this fester! You deserve to live freely, not cooped up in a room.

Yes, I was invited specifically to fill someone's space, that was the only reason. And I was the 4th or 5th person she asked to fill that space. I was very much a last resort.
I'm absolutely willing to try, but I don't need how. I'm autistic so I need direct instructions. How, exactly, do I go about meeting them for the first time? Where? What do I say?

Ah ok, did you at least get to know the girls who invited you well enough? If not, fair enough. It's a shame they haven't reached out to you. I would have if I were in their friend group.

Socialising doesn't come with instructions. Speak only if you want to. Go with the flow. Do you want to know them? If so, start with what course they're studying, how they are feeling about 3rd year. You dont even need to seek them out. Keep calm and collected, do what you need to do around the house. Make your food, maybe they'll be in the kitchen too! Could start talking about what you're making for example. Watching TV etc.

Just dont be a hostage ok? Even if they turn out to be just housemates at best, just keep it friendly and you gotta try make friends elsewhere. Nothing wrong with that and you won't be the first or last.

Good luck I'm rooting for you!

No, not at all- when I was first added into the house group chat, I knew this exact situation would come about if I rocked up to the house in September to a house full of strangers, so I tried to organise a meetup with everyone beforehand (we were all in the same city abroad) but no one seemed interested. No one's messaged me or said hi or anything since I moved in.
We're all doing the same course, and asking 'how they're feeling about 3rd year' is NPC dialogue, sorry.
I'm physically incapable of doing what I want to do around the house, which is the problem. So that's really a lot easier said than done. Today, instead of enduring a full bladder for 20+ hours like I usually do, I peed in a bottle for the first time. Which, as a woman, is rough. I'm not just a hostage- I'm becoming dehumanised.