Definitely go slow with it, and so glad to see that it's getting a little better for you in the nap departement. Sleep is such a slow thing to improve upon, so that plus you being sleep deprived on top of it makes it such a challenge.
My twins took FOREVER to adjust sleep times, but E not so much. I think temperment plays a large role in sleep needs and sensitivity to change kwim? Even if you went in increments of 5 mins and lengthened your wind down routine a little bit.
You're doing great - keep up the good work!