Macarons keep coming out wrong

[cth20]

Hi! I made macarons for the first time and they came out pretty good, with the exception that the shell was a little hollow on some (I’m guessing I didn’t get as much air out as I thought). I tried to make another batch last night and the batter was too runny. They never baked on the bottom and the shells seems very flimsy and cracked if I picked them up (almost appeared wrinkly after they cooled) so I had to throw them all out. I believe I didn’t whip the egg whites enough. Now I made a third batch, and same problem! Bottoms are sticky and tops look wrinkled. Except I think that I whipped until a stiff peak was formed (photos for reference). Using the same recipe as the first time too! Any help would be appreciated! Thanks

 

[retired baker]

They would come out better if baked on paper. The mat is causing them to under cook.