Are the voluntary days that the questioner fasted counted as making up for the days he missed in Ramadan due to illness, and what is obligatory upon him?

The days you fasted with the intention of a supererogatory (nafl) fast are not considered make-up (qada') for obligatory fasting, due to the absence of the intention for make-up. It would have been better to prioritize making up the obligatory fasts before volunteering for supererogatory ones, and before the arrival of another Ramadan (definition). You must repent to Allah for delaying the make-up. You should make up the days you missed fasting and feed a poor person for each day as expiation for the delay without a valid excuse. This is the opinion of the majority of scholars.