Polyamorous and finding lesbian dates

I'm 18 and I've been with my boyfriend for 4 years now, we're living together at uni and everything is going great with us. I'm polyamorous which my boyfriend is completely accepting of.

For about 8 months last year I was dating another girl as well as him. The girl moved away and it ended pretty naturally but ever since I've been really struggling without having a girlfriend. I feel like I have no right to complain because I have a perfect relationship and I'm extremely lucky to have such supportive family and be in a position where I can live with him already at such a young age.

But I really really want a girlfriend. How and where do lgbt+ people even find dates, people to talk to etc? Does anyone know of any dating apps that are bi (not just gay) friendly? Or online forums etc? Idk any advice would be welcome. Thanks