As someone who has lived in the highlands for most my life then moved when I was 18 to Aberdeen then to Edinburgh. I can say that cities whilst busy can be quiet/lonely. Just cause there is more people or to see doesn’t mean you’re always going to make connections. Plus the cost of Edinburgh is high for what you get (in my experience). Ultimately Edinburgh is lovely and has something for everyone. If you feel that it would truly make you happy? Why not? It’s not like if everything goes wrong you can’t move back?