Disco 2 headliner

My disco 2 started leaking from the sun roof. After researching I decided to try and fix it myself which im happy to say the leak is now fixed (abit of DIY with the drain pipe). However I now have a problem with the headliner. When I have tried putting it back up it doesnt sit flush against my window screen and sunroof/light console on the drivers side. I have tried researching ideas on what could be the problem or ways to sort it out but ive had no luck. Has anybody else had this problem? If so have you sorted it out and what did you do?

Btw it is not the material 'sagging' (seems there are many threads about this) its the whole thing