Don't be mad at yourself! I had trouble with that, too. (Heck, sometimes when I check my own blood sugar, I don't get any blood either and have to prick a second time...and I've been diabetic for over a decade.) But it got better. I used two tips that I picked up here: microwaving a sock full of dry rice to use as a heating pack to gently warm up the ear, and putting a thin layer of petroleum jelly on the spot you'll be pricking so that the blood will bead up when it comes out instead of spreading through the fur. My girlie absolutely
hates having her ears touched, so that aspect of it never got better in the relatively short time I was having to test her, but getting blood out
did get easier.
I remember reading that most cats tolerate ear pricking really well because they don't have a ton of nerve endings in that spot (not like your fingertips if you were to prick yourself), so be patient with yourself. You likely aren't hurting him. Is this roughly where you're poking?