Well there is no deigning the relative ease of making friends in the JW world especially as a teenager, especially at assemblies.
Assemblies and conventions always smelled like teenage hormones. Sort of sweaty with a trace of something sweet. But when you leave the tooth the friendships can melt to just a slick of moisture on a road.
The key about new friendships is to do what has worked for you in the past. Meet regularly with people who share a similar idea, interest or commitment.
It could be a volunteer group (volunteers are the best people ever).
A sports team or a fan group of a particular team.
You need to hook up with a group that meets on a regular basis, has an interest that you can relate to and/or share. Is made up of a variety of ages and male/ female mix. Just like a KH.
In other words you can duplicate the JW experience with regular meetings and activities, a special way of looking at things and share a common language.
It's when people become familiar ....... that you get a space to 'go out for coffee' or other beverage. A friendship that can grow organically which is the best kind of relationship. Nobody owes any one anything it's just that you enjoy one another's company.
I'd start with ex JW meet ups....... look them up on google and see if there are any groups in your area of the world.
Travel groups.....somewhat expensive. But a great place to make new friends.
Being a volunteer willing to give up some time without pay.
A liberal church that has a good social feature.
An online dating service.
A Mom's club is also a Dads club if you have a child.
School if you need a trade skill or some higher learning.
I easily knew 100 people really well when I was a pioneer.
Out with my wife for the last five decades.
I am still friends with 100 people of which only one is still an active witness ie. PIMO.
My final thought is to call or email people for that meet up over lunch or just a coffee.
In a man's world most guys don't call another guy but every time I arrange a lunch the guys will say 'this is great we should do this more often' but they don't call or email. So I just go ahead and invite them.
My wife is great at that and her women friends look forward to the meet ups.........but guys are more remote.