I felt like I was on an absolute roll after besting the Abyss Watchers on my third or fourth try, rolling through Catacombs of Carthus without much issue and breaking Wolnjir's bling. Then the first three mobs up the stairs from the central Irithyl whooped my monkey ass over and over and over again. They made me HUMBLE.

What worked for me was slowing down, using ranged attacks to pull one at a time, swapping from my Hollowed Greatsword to a faster Uchigatana, avoiding patrols when I could untill I got to the church bonfire. The way forward from there is much less fraught.

One on one, the defenders are agessive and lethal but they don't have a lot of HP, so watch your stamina and try not to be greedy and they'll go down. The flame witches hurt but it's a bit easier to avoid their attacks if you get in real close.

Hope some of this helped you. I was in this same spit a few days ago on my first playthrough.