Fear of planning-failure

I’m in a constant battle between what I planned and new things that arise since planning— even when I budget overflow time. This morning I tried getting curious about two parts of this: 1) why I believe I can’t prioritize new requests during overflow time, and 2) why checking my calendar feels onerous.

Here are two models:

C: I don’t end up needing the overflow time that I planted into my schedule to accommodate the daily unexpected (like taking my elderly mom to the ER or driving my kids to school because of inclement weather)
T: I don’t know what “extra” thing to do first during this free time block
F: paralyzed
A: spin in self-criticism, do lots of busy work, hand-wringing, fretting, jaw-clenching
R: I waste time & don’t move closer to my goal

C: I avoided checking my schedule to see where I could place a new request.
T: If I check my schedule, l’ll find out I messed something up and confirm my belief that I’m not a planner (so I’ll never succeed).
F: dread
A: avoid checking calendar, avoid responding to the person making a request of my time, generate frenzied energy, behave irritably to people around me, self-berate
R: I mess something up in my calendar & feel SOOOO bad, soooo low, sooo convinced I’ll never make it to my goal. I weep.

How can I leverage my models to help myself overcome my limiting thoughts?

Thank you.