I had a somewhat similar experience. No PhD but I had always hated math as a kid learning nothing but, as you say, rote computations in school. By chance I stu

I had a somewhat similar experience. No PhD but I had always hated math as a kid learning nothing but, as you say, rote computations in school. By chance I stumbled on Frege's philosophy of mathematics/investigations into the foundations of mathematics in college and suddenly math was actually really interesting. I find proofs, set theory, algebras, and other mathematical domains closely related to logic way more fun than rote computations. I recall thinking I could have really fell in love with math and maybe even excelled at it if my schooling had ever given me so much as a hint that this stuff was also part of mathematics and it wasn't mere repetition of the same old computations, and that all those formulas build on each other and actually have very interesting justifications.