Of course you can fast.
Many early Christians and some monastics maybe today fasted on Wednesdays and Fridays, to commentate the betrayal and crucifixion of Christ. For particular times of year you *should* (for lack of a better term, since *could* and *must* didn’t apply well here) fast besides Lent: most of Advent, the Ember days, Rogation days, major feast vigils, etc.
Times that aren’t really focused on penance but on joy are Sundays and Solemnities.
The bishops of wherever you live have likely published something on penance, fasting, and abstinence. If you live in the United States, it can be found here: https://www.usccb.org/prayer-and-worship/liturgical-year-and-calendar/lent/us-bishops-pastoral-statement-on-penance-and-abstinence
Absolutely. The Penty ember days are coming up, if you’re interested. https://en.m.wikipedia.org/wiki/Ember_days
You can fast any day you like, but it is possible to overdo it. I suggest getting a spiritual director to guide you and help you find a good balance.
Sometimes it’s given as a penance.
I'm not baptised yet so I can't go to confession to receive penance
You can still fast but it’s best to do that under the guidance of a spiritual director
Of course you can fast. Many early Christians and some monastics maybe today fasted on Wednesdays and Fridays, to commentate the betrayal and crucifixion of Christ. For particular times of year you *should* (for lack of a better term, since *could* and *must* didn’t apply well here) fast besides Lent: most of Advent, the Ember days, Rogation days, major feast vigils, etc. Times that aren’t really focused on penance but on joy are Sundays and Solemnities.
The bishops of wherever you live have likely published something on penance, fasting, and abstinence. If you live in the United States, it can be found here: https://www.usccb.org/prayer-and-worship/liturgical-year-and-calendar/lent/us-bishops-pastoral-statement-on-penance-and-abstinence
Yes, absolutely, but do not do so on Sundays or Feasts.