Post-spay concern

My 5 mo. old kitten was spayed 3 days ago and I've been keeping a close eye on the healing incision. The stitches are holding, but around the incision looks a bit pink and a new pouch has developed under it on her tummy (which used to be flat,)
and the pouch looks pink. I'm worried that my very active kitten is having post-op complications. I couldn't keep her from frolicking and jumping about at all, she was hyper from the moment I brought her home (but I had hoped for a reprieve of some mellowness while the drugs wore off). Any advice?

That looks like an infection to me just because of the red and the puffiness. Is it hot to the touch? Probably need to see your vet for antibiotics.

It's firm, but not overly warm. Does that make a difference?

Well with my kitten when she had hers, the stitches bulged out a bit and it eventually went away, but they didn't bulge that much. The pictures make me worried. Is there a vet that you can send the pictures to to ask their advice on whether to bring her in or not?

After her spay, my kitty had firm swelling at the incision site a couple of days after the spay. It wasn't hot to the touch, no redness, no discharge, and it was less than half the size of the lump of your kitty's, and the vet said it was an abnormally-sized lump. So, these pictures are definitely concerning to see. I had to get an ultrasound done for my cat, just to be sure, but it ended up being a suture reaction and went away on its own after a week or so.

With my kitty's lump, the vet couldn't push/nudge the lump back inside the body with her fingers (if she could she said it would indicate a hernia, as the kitty's squishy insides are being pushed back through the abdominal wall). So, because it was a firm lump, I was told that the lump could either just be fluid from the healing process, or it could still be a hernia but a more severe one in which the abdominal wall has started healing around her protruding insides and are holding/constricting them (with the possibility of the constricted intestines eventually getting necrotic... let me tell you, lol, it was terribly alarming to listen to). But my kitty's lump was also never this red, so I agree with others here who think it could potentially be an infection/abscess..

I have a vet appt for her at 3:30 today :/ I hope my baby gets what she needs and feels better soon. Thank you for the advice!