Apparently unable to seed cells in a 12 well plate

Hi all,

I've been doing mammalian cell culture for about 6 months now - I'm good at all the important steps like RNA extraction, protein extraction, etc. I can thaw, freeze, seed cells fine at the Petri dish / 6 well plate scale.

Somehow, no matter what I do - my 12 well plates have cells clumped in the middle of each well. This makes it very difficult to move on with a transfection I need to do because my cells also grow super fast - they'd overgrow by the time I harvest them if they're not perfectly spread out at about 10-20% confluence.

Things I'm already doing: adding medium before adding the cells, tilting the plate up-down and left-right, leaving the cells on the bench for about 15 minutes before moving to the incubator.

I can't seem to get this right and it's really frustrating for me but also I don't need my PI to berate me over and over for not getting results.

Thanks all!