Just caught my neutered male trying to mount. She has been meowing loudly, is rubbing herself against everything and is doing that "horse like" jumping followed by bursts of speed. Very playful overall. Is this normal?
You should take your cat to the vet. During the spay, some ovarian tissue may have been left behind, and it is still producing hormones that cause her to go into heat (this is called Ovarian Remnant Syndrome).
Your vet will do some bloodwork to check her hormone levels, and if the bloodwork and physical exam indicate that she still has ovarian tissue, another surgery will be needed.
Your neutered male may mount just for instinct. He may not even know what he's doing. I had a male cat that did this to my female cat every once in a while. I wouldn't use this to confirm your cat is in heat.
I also have a cat that, does what I call, "fish jumping" (what you call "horse-like jumping"). It's just how she gets my attention.
If your female cat is young, it will be hard to tell if her surgery was successful. She may exhibit all kinds of crazy behavior just because she's young. So you do need to take her back to the vet, as Zaralynda recommends, to have her checked out. Nothing may be wrong, but it's better to know now, instead of waiting, in case a correction is required.
I hope this helps, and I wish you and your cat family the best!