Struggling 😔

I'm 24 in 2 weeks, partners 26.
We have a 3 year old daughter (surprise pregnancy) 
We decided to try to conceive baby number 2 back in February so I took my coil out and since then literally nothing. I'm now feeling extremely depressed. I'm literally desperate for baby number 2. 
Everybody around me is getting pregnant and I'm insanely jealous while being happy for them. I've now convinced myself it's never going to happen,does anybody have advice please?