Struggling with Loneliness and Lack of Social Support

I have a very very hard time being alone/feeling alone. For years I was “friends” with a lot of people who I eventually realized were not good friends at all and were damaging my mental health. I dropped almost all of my “friends” at the same time since it was a big friend group full of immature and drama loving people I couldn’t stay friends w some and drop the others. Now I feel so alone. I have like 4 people I talk to now (not including my boyfriend). 1) I talk to everyday but only see her like once a month or every other month 2) I talk to maybe once a week and see her maybe every other month. 3 and 4) I talk to every few weeks and only see them every 3-4months. It’s gotten to the point where I have panic attacks when it’s time to leave my boyfriends house because I know I’m going to be completely alone until I see him again. The only socializing I do is with my boyfriend and his friend group, they are okay but not my favorite type of people and none of them I can see myself being close with. I don’t even know how to make friends since I dropped out of college after a month, and I had a bad reputation in high school so I can’t become friends with anyone I went to school with. I thrive off of socializing because when I’m alone my head goes very dark places. I’m just so lost and alone and I feel like I’m gonna be alone forever. My boyfriend and I have an amazing relationship and are both serious about being together forever BUT if something happens and we break up idk what I’m gonna do because he’s really the only person I have