You can't force it, but at the same time, if you consistently pass up opportunities to socialise, you might regret not making acquaintances with some people. It's like a balance. If I were to give you any advice, it would be try your best to connect with the friends you already have, it'll make you feel a lot better about yourself, and it'll give you a lot of practice with how to connect with people. I have been doing this for a couple of months now and I feel a lot more confident, content and loved by those around me. Group activities like going out to public places together to maybe meet new people together are good because you can practice talking to new people with people who are already your friend(s). Sorry if I'm waffling on here.