Uncontrollable vaginal discharge, what's happening?

I'm 16 and have been sexually active with my boyfriend, who is also 16, since October last year. I've had the implant for over a month now and sex is legal in the UK at my age so don't talk about that.

Basically, the past few days I've woken up in the morning and I sit there for a few minutes trying to wake up a bit, then once I move I basically just leak some kind of liquid. It's very watery (like urine) but I don't believe that I keep wetting myself every morning, because it's not that sensation (it feels like it's inside my vagina).

I sit on my heel to stop the flow because if I sat normally, it'll still come out. I try sucking in while I run to the bathroom to sort myself out and by the time I get there it's running down my legs..

This has happened once or twice before in the years I've been through puberty, but it's never been this consistent. The only reason I thought of urine is because I used to have bladder issues, but they're not a problem any more.

It makes me feel gross, and I'd like an explanation please!