Strong draw being -2 in material

A difficult game against a 1900 rapid player. My opponent played better in the middlegame and managed to get two connected passed pawns. I had to sacrifice my one bishop in order to neutralise them. Despite the fact that Stockfish gives +2-3 advantage to my opponent I had a drawing pattern which was very hard to be defeated by a human... (a not GM human to be more accurate). I offered a draw which was rejected and my opponent at some point MISSED a winning tactic when he had the chance to put me in zugswang!! Look at move 66. After this he was so frustrated that he could not find the way to break my defense that he even sacrificed his one bishop to open my position, but this was very good for me as I could never lose a game where all my pawns were protected by my king and everything was at light squares, while my opponent had a dark square bishop... HOWEVER, on move 80 it was my turn to MISS a bishop sacrifice which would allow me to promote a pawn to a queen and win easily the game... After 10 more moves the game settled sown in a draw by 3-fold repetition...