Fading friendships and a venting tangent I guess

Ok so I'm an introvert and I like spending time alone. The problem is now I've spent so much time alone that I've forgotten how to be around other people and form meaningful connections. I'm doing a course but I don't have any friends in it. It doesn't help that most of my classes have been online this year. I'm 25 now and I still have 2 friends from high school that I see semi-regularly. There's a few other friends from high school that I might see/hear from a couple of times a year but we don't really talk outside of that. I wish there was a way I could somehow become closer to my friends again but it doesn't seem realistic. Everyone is either quite busy with various things in their lives (study, family, partners, work), lives far away, or we don't have much in common anymore.

The two friends I do have I try to be a good friend to them but it just never feels like enough. I feel like I'm constantly letting them down because they usually have to be the ones to reach out to me and I know I need to put in more effort but I just don't think I have anything to offer anyone anymore. I feel like I don't have the emotional capacity to take on the needs of other people because I can't even figure out my own needs. One of my friends constantly tries to open up to me and get me to open up as well but when it gets to really personal things I don't always know what the right thing is to say. So I'll say something like "that sounds like it would be hard" or "I'm sorry your feeling that way" and it just feels so lacking in emotional depth even though what I'm trying to do is show her that I'm listening. But sometimes my mind will go blank and it makes me feel terrible because I'm still trying to figure out how to respond and meanwhile my friend has just confessed something really personal. I don't know how other people just naturally know how to comfort others and talk about deep things because for me this is definitely not natural and is in fact really difficult. Whenever I think about the times I failed to give the right kind of emotional support to either of my friends it just makes me want to isolate myself and withdraw from everyone even more because even when I'm trying to do better and be there for them I still can't get it right. But then I'll feel bad for isolating and I'll think that I should reach out to them but by then they will usually have already reached out to me so the cycle continues.

I also just feel so ashamed of where I am in life and how lost I feel and I don't know how to really communicate this with anyone because I feel like I want support but if I can't support my friends very well then why should they support me? But then by not telling my friends how I'm feeling this is just another way I am distancing myself from them so I just don't know what the right thing to do is.

Ugh I don't really know what I was trying to accomplish by writing this all out. I guess I just wanted to get it off my chest. But if anyone has any ideas on how to be a better communicator for my friends or how can I stop isolating all the time, or if you've gone through anything similar I would welcome your opinion/advice.