I think T/Monkey meant the overall render, instead of one thick coat,, bring it out in thinner coats as we have been saying earlier.
Ahh,, yes (suction) you've got it. Yours wont fall off, (now it's on) but it makes it more difficult to work with. You would normally put a waterproofer admix in the render which more or less eliminates any suction.
When you put on your next coat, give the wall a good wet down,,, not overwet though, then leave it for a few minutes before you coat onto it.
If you have a problem with suction, even though you have wet down the wall (i'm assuming you never used waterproofer), give the wall a coat of PVA, then "let it dry" (kills the suction),, then pva again, and coat onto it while it's still tacky. Suction on some jobs can be a good thing if you can handle it,,, on other jobs, especially roughcasting,, you dont want any suction at all.
The size of the job you're working on just now, is perfect for learning to render/plaster.