Chat with the chief: Introvert

I’ve never been much good at keeping friends, especially female friends. 
I had different groups of people that I spent time with in elementary school, middle school, high school and now college.
Since I left home three years ago, I lost touch with all but one of my friends from high school and I’m afraid I’m going to lose touch with my college friends come graduation in May. 
Why am I like this? I can say it’s because I’m busy or because I don’t have any free time but at the core of it, I think I can’t keep friendships because I’m an introvert. 
I’ve never had trouble talking to new people when I’m out, and I’ve been told I’m friendly and easy to talk to. When it comes down to it though, when I have a little alone time or a night to myself, either A) I can invite someone over or go out with people, or B) I can curl up on the couch with a cup of tea and read a book, or watch my favorite show. 
I can count on one hand the number of times in the past three years that I went with A. 
The worst part of all of this is that I like female companionship; I like having someone to confide in and spend time with that isn’t my significant other or my mom (no offense to them). 
But in my head, I create this huge gap between friends that I have a deep connection with and friendly acquaintances, and more and more lately I feel like the people that I consider friends are drifting into acquaintance territory, and I don’t know how to stop it. 
To make things harder, I suffer from anxiety, so every time I do puck up the courage to invite someone over or make plans, I talk myself out of it because I assume it will be awkward or that they don’t want to spend time with me, otherwise they would have initiated it. Right?
I don’t think social media does anything to help this; it gives us the illusion of friendship without any real connection. You like posts and comment on pictures but you don’t really know how that person is doing or what’s going on with them. 
Beyond that, you see every time your friends hang out or do something without you and feel all the worse because you want to be out there; you want to be the type of person that chooses A over B.
I know I’m running the risk of sounding whiny, so I’ll end on this: I think there are a lot of Bs out there, and I don’t think there’s anything wrong with that. Loving spending time by yourself isn’t a crime. 
I have a couple people that, even when we don’t talk for weeks at a time, I can rely on them to be there for the big things and I know they feel the same way. For me, for now, that’s enough.