How to get rid of lifelong dandruff in a dry climate?? (no pictures shown)

title explains it all but i need help from people who can know more, be more understanding, and without knowing me..
im a severely depressed person, have been since covid. now im 18, i shower at most 3 times a week, (i know it's gross) plus i was born with eczema. not to mention i also live in colorado, so the climate here is super dry.
i have somewhat curly hair (2b/c) but it's pretty short, with the longest at my collarbone.
issue is, ive had dandruff my entire life and i have no idea what to do about it.
if anyone has some ideas for me to help, please share, just keep in mind my mental state.