Hi Angela,
I had a really rough time too after my reversal surgery and felt much like you described. I would say it took about a month before the intense burning and itching died down. It was so bad sometimes and I felt helpless. I also used a sitz bath or often just took a regular bath and would sit in the water for an hour, as it was the only means of getting any relief.
It takes some time for your body to get used to its new design. The anal area is not used to having such frequent and watery stools, so it needs time to adapt to the new conditions. I also got fissures which were extremely painful and made me feel like I was passing shards of glass.
If there is ever a time when you're not feeling irritated (maybe when you first wake up), that is when you want to apply the Calmoseptine or other barrier ointment. If you wait to apply it until you've already gone to the bathroom, then it is too late and may even make matters worse.
I would recommend purchasing a bidet if you haven't already. I didn't want to spend several hundred dollars, so I purchased one called Blue Bidet BB-20 Portable Bidet. If you do a search for it, you'll see that it's very small and something you can just keep next to the toilet. I've been very pleased with it, and I think it only cost me about $20. Definitely worth the money because you do NOT want to use toilet paper all the time, as the excessive wiping will only add to your misery.
Feel free to ask more questions, and I'll do my best to answer them. Things will get better!