Welcome, OT! Well--I looked up the origin of knot, thinking you might be able to add ...phile onto the end of a root and get something at least semi-meaningful, but here's what I found at Dictionary.com:
Origin:
bef. 1000; (n.) ME knot ( te ), OE cnotta; c. D knot, G knoten to knit; (v.) ME, deriv. of the n.

None of the synonyms for knot jumped out at me as good candidates, either. Knot nerd sounds fine to me!