Leaking Fluid

Abby
So over the last couple of weeks I've felt my pants being more wet than usual. I've started to wear panty liners and usually it's semi dry when I come to change it with a yellowish tinge. Sometimes when I get up off the loo a bit of fluid leaks out and I end up having to go back to sit down to make sure there's nothing else. 
Anyone else experienced this? Is it urine or amniotic fluid?
I'm 30 weeks today.