Placing a knight on d4 looks like a decent plan even if your opponent avoids the fork, obtaining the d4 square and placing a knight there looks good, if the knight on d4 happens to fork king and queen than great but you shouldn't make plans that require your opponent to cooperate.
You're right it wasn't a solid plan, but I wasn't just hoping my opponent would play along. From that move I didn't see anything else I could try for bettering my position or gaining material. It almost looked like a drawn game to me.
I wasn't beating myself up. I was sort of happy that I saw a plan and tried to develop pieces around it instead of mindlessly moving pieces hoping I'll later see a solution like I usually do. I didn't expect him to resign, I have some games that go on and on even after a queen capture.