How to socialise after 3 years of isolation

I’m 20 years old and have been isolating since just before the pandemic around January-February of 2020

When I was 15-16 I got diagnosed social anxiety, general anxiety, depression when I turned 17 I started to get really bad health anxiety and was diagnosed with psychosis at 18

Before I used to go out to partys and social events quite a lot and didn’t enjoy them as much as other people but now I have stopped going I have realised how important it is to have a social life

I want to get out of this but I feel I have forgotten how to socialise, make friends and everything else and have no idea how I would even go out

I rarely ever speak to my school friends and could ask them but feel like a bother and I don’t know if they would want to due to my mental health which has gotten better but not completely out of the water

I’m currently doing volunteering at a charity shop I’m also working on my diet, my exercise and have been consistent for a month with that my confidence is definitely better. I haven’t put myself in challenging situations to see if that has changed though

If anyone’s got through social isolation and has got any tips or ideas let me know

Thanks