That totally sucks. But you had both a LIS and fissurectomy which prolongs the amount of time you need to heal. Anal surgery is very painful due to the amount of nerve endings down there. I am curious as the why he did a fissurectomy if your fissures didn't look that bad. Usually an LIS is sufficient.
How much motrin are you taking? You may need to take 800-1200 mg at a time to get much of an effect. Can you call your doctor and tell him about the pain. Maybe they can call in a prescription as long as you are keeping things soft and don't get constipated.
Post surgery can be so tough because the pain can be worse than what we were dealing with initially so it can be easy to wonder what the heck we've gotten ourselves into but it will get better. Take the sitz baths 3 times a day. That really helps with the pain as well.
Healing takes so long in the anal area precisely how you have described it. You can't stabilize the area because you have to use it to poop so it is very much a one step forward, two steps back.