Wanting to make lifelong friends is like wanting to meet your soulmate while supermarket shopping. A bit intense and vanishingly unlikely.
Where I've made friends - school, fan clubs, university, drama clubs, music groups and choirs, NCT classes, toddler groups, PTA and school things, through work, at book groups, in online chat forums, at adult education classes, at exercise and hobby classes, while volunteering, at gardening groups, at a walking club, debate salons at the local museum, by crossing paths repeatedly and striking up conversations...
The way to make friends is to be around people, be interested in them, be fairly confident, and not mind if it doesn't pan out.
I probably have 20 to 30 so people I could meet for a coffee or a drink with, whose company I really enjoy. A couple of close friends are wonderful, but don't sneeze at the idea of more lightweight friendly relationships - they can be a source of a lot of happiness too.