Hi . I can honestly say "I know how you feel". I had perianal disease with fissures, fistulas and abscesses for 30 years before getting an ostomy and having my rectum removed in late 2020.
I had many operations for either lancing, adding with a seton or cutting it wide open and letting it heal. It is very frustrating at how long some of them took to heal over but yes, in my experience, sometimes it can take months because it has to heal from the inside out and if the inside is not healthy, it won't heal. It depends on how deep the infection goes. I too was taking sitz baths every day but I added Epsom salts to try and speed up the healing. I'm not sure if you use those but you might want to give it a try.
I know taking antibiotics are bothersome but at times I was glad to take them. Maybe there are different antibiotics to try, not sure which ones you are on.
In my experience, it's better for it to take months to heal properly than to have it heal over quickly and reabscess.
Hopefully, things work out well.
Let us know how you get on.
Vern - Crohns/IBD Team Member