You've already had some good advice. I'll add this -

Since you are already comfortable making backing tracks for famous songs - go to one of the sites that post lyrics from wannabe lyricists - find one that moves you - what do you feel hear when you read those lyrics. Offer to put it to music. Will you find the next number one hit there - probably not but you will get great hands on practice.

Do what you can do now. Learn more as you go. Read articles, books and watch any videos you can find by Jason Blume. There are many great songwriting books teachers and online classes. Jason's road to success is inspirational and he's a great teacher who I always recommend for anyone interested in learning to write songs.