I was playing as the sophons and in early game about 30/40 turns a epidemic start, I have -14 pop every 8 turn and -2 pop every 10 turn, and only 3 systems for about 12 pop in my empire.

So when the epidemic start my pop drop dramastically, ok (even if my economy and science died this turn, it's a cruel world, with 4 cravers factions ...). 

To minimize the effects I start building colonization ships and to colonize planet but an other strikes and my pop is 1 on every planet, my colonizations things stop because I don't have enough population. So I cancel colonizations things because no growth but since that moment, EVERY system is stuck at it's size and don't grow. None of them is building anything special and they all have a positive food income.

I loaded the game and nothing change.

Is it because I have some sort of still 20 pop who should have die but didn't so I have to wait like they were creating before growth start again or is that a bug? If so is there something I can do?

 Unfortunately all of my saves are after the epidemic...

Thank you for helping me