I had a medical abortion a few years ago and while the experience obviously wasn't great, it really was ok. I made the right decision for me at the time and I don't regret it. I remember being in your position and desperately searching online for reassuring experiences. I think the people who have had positive experiences, or at least ok/mundane experiences, are just less inclined to write about it online.
You've said you have no idea how many weeks you are- are you able to purchase a digital pregnancy test which could give you some indication of how many weeks? Or did it just say 3+. Have you thought about what you will do if you are further along than you think you are and you need a surgical abortion? Or if you are even past 24 weeks? There is a big difference between a 6 week pregnancy and a 10 week even.
I was 6 weeks and it felt like really, really bad period pain. My experience of it was that the pain comes in waves (a bit like actual childbirth) and you will gradually lose tissue and blood. I can't remember specific details anymore but I think I did need at least 3 days to fully recover, although I know people who have been in work only a day or two after.
It's not a nice process to go through alone or have to hide though so I would recommend that you are with someone you trust and feel safe with. Is there a reason you don't feel comfortable talking to your parents?
At the time I was warned that when I had my first child I might feel differently about it or look back and have regrets, so be prepared for some feelings to be dredged up when/if you do one day start a family, but personally it's not something which has affected me and I've barely thought about it. It did help that I was so early on though. I know I would feel differently had I been later.