Hi Spl SpL
I finished highschool a few years ago now. I went straight to uni the following year. However on the three months between I didn't contact anyone from high school, in fact I didn't really talk to anyone for almost 2 years into uni. I made aquitences at uni, but I have now finished my degree and like year 12, I don't talk to many.
I'm not sure entirely how you are feeling, but I know that I was scared. I was worried that I would change and that my friends would change, move on to bigger and better things, find better friends, so I pulled back to avoid rejections, thought I would make that change instead.
Eventually some of my friends from school reached out, mostly for 21st birthdays. And despite feeling nervous and embarrassed, I went, I reconnect with them, and yeah, some of them changed, but only in a way where they matured and more reasonable about things. Surprisingly none of them were weird about my silence. We picked up where we left off. Now even though I live a while away from them, we keep in touch. It could be weeks or months we go without talking or seeing each other, but we're all still good friends.
I think during that period I didn't really have friends, I was trying to find things about myself. During school I was souly focused on study and had a lot of family problems. Going to uni let me get away from it all and think. At the same time I though they wouldn't like who I was and vice versa. Getting past all that was difficult for me, after a day or even an hour of socialisation I just wanted to retreat back to my room and hide. I still get like that from time to time actually.
I'm not entirely sure where I was going with this story, but maybe there is a deeper reason for why you are doing what you are doing and you haven't figured it out yet. I hope that your friends are understanding of what you are going through and how you're feeling.
Finishing school is definitely a scary time too. There is so much pressure to 'succeed'. Go to uni, get a career, buy a car and a house have a good social life. It's hard. You need to do things at your own pace.
It's difficult to reach out to others when you haven't for so long. I just did it recently, all I did was send a hello and bam conversation happened. So maybe just send a hello?