I seriously doubt if she is in heat again, especially if she is still nursing puppies. Mounting behaviour is just "playing" and can sometimes, according to some "experts", have more to do with sorting out pack order (dominance/submission heirarchies) than anything sexual.
In order to successfully breed, dogs need to be able to achieve a tie, which you already know, and some inexperienced males need help with that and inexperienced females need to be supervised to make sure no one gets hurt. https://barkingroyalty.com/breeding-...-need-to-know/
That said, I commend you for doing the extra work and expense to get a vasectomy for your little guy. Doing anything "controversial" is going to be a headache, but our dogs are worth it.
Gonadectomy is practiced in veterinary schools until they can do it in their sleep, but less invasive procedures require "new" skills and new ways of thinking. It is not easy to find a veterinarian who will even listen to you. Most of my conversations end with "the spay and neuter clinic has vouchers if you can't afford it".
I am assuming that you are in the US, of course. In many countries you would be able to get a tubal ligation for your dog just as easily as you can get one for yourself.
If you were able to find a referral for a partial spay, that is worth celebrating: https://www.dogforum.com/dog-health/...ectomy-364835/
but do be aware of the science behind ovariectomy vs hysterectomy; my girls (now plural) will still have the same risk of spay incontinence from estrogen deficiency but can keep their uteruses with no risk of pyometra.
Stump pyometra is possible if the surgeon doesn't remove the entire uterus during the hysterectomy. However, your bitch would continue to cycle with no "mess" and her endocrine system would remain intact.
I would love to discuss options to gonadectomy with you via PM. The mods have been very polite about asking me to let my public thread die.
As a new dog owner, I don't always know what controversial topics are analagous to breastfeeding/bottlefeeding and home birth/hospital birth. As an experienced forum user, I do know how nasty these "flame wars" can become.
So to make a short story long, no, I do not think it is likely that your bitch is coming into heat again.