AF Angel, do not lose faith on healing on your own yet, in my experience with my fissure I was just like you, after 4 months and ups and downs, to now 8 months later with the last two spams free and painless BMs I almost forgot today that I had a "fissure" problem thats how well I am doing.
But the road was not easy, you have to stick with the routine that was working for you.
Yes I can not get tired expressing that soft stools, lubrication before and after a BM is critical, keeping the area clean even inside after BM, gently wiping with vaseline to avoid later on irritation. I no longer using the nitro cream I stopped back on month 4, persevering and the feeling that I can beat this is what is getting me to what I am now.
But like everything if my fissure re open to the point of day 1, I will have no problem with surgery and will do it right away.
Is a hard decision to make but you still have time, after the successl sucess you had so far.