What happened to my sleeper??

Ugh you guys, my 12hr sleeper is waking up so upset every 2-3hrs for the last week. We recently transitioned her out of her bassinet and into the crib and ever since then, she's waking up. I think it's cuz she isn't cozy and is exposed. She's also super squirmy and moving all over the place in it. We have an a/c unit in her room too, but we've tried just a fan in case it's a temperature thing, but no better luck. How can I make it feel cozy without loading her crib up with blankets and pillows?