Of course you can refill freezes, but you need enough credits to do so. You accumulate credits as you complete lessons and hit targets. So OP was, effectively, living for a period off the riches he had accumulated over almost 10 years (!) of efforts. That's not easy.
That is a fair point. I went back through my history in the app to figure out the real numbers: First day of use: 11th Dec 2014 First missed day: 19th Jun 2017 (921 days later) First freeze use: 20th Oct 2020 (2,140 days after first day of use) The missed days were down to (IIRC) time zone crossing and patchy internet, I can't recall if Duolingo let you off here or if there was leeway in the streak calculation. Those…
Do you have a sense of what kept you going? And what about Duolingo helped?