I can follow a plan, but I can't design one — now what?

You tell yourself the problem is design. It is not. You can read a map once someone draws it — you simply will not draw the first line yourself. That is not a missing talent. It is a refusal to act without certainty, dressed up as a limitation. No one designs a plan from nothing. They copy a shape that worked for someone else, then cut it down to fit their own case. You are asking for a gift that does not exist. What exists is a habit: write something rough, walk it, see where it breaks, fix that part only. The work in front of you is smaller than you think. Not "build my career plan." Just: find one structure, write one version, test it for two weeks. You already know how to follow. Use that. Follow your own rough draft before you demand a finished one.