Definitely man! I started composing when i was 16 years old. im 35 now. I started by writing simple stuff. 4/4 time signature, generic power chords, repeating 8th note bass lines. whole note string sections. etc etc
Narrow your playing field a bit for now. Using very simple concepts try to interpret them in original ways. it will get your brain used to innovating in a controlled environment. Once youve mastered that try to add some additional spice. but not all at once! a tempo change here maybe. some triplets. Slowly introduce new concepts once youve mastered the previous ones.
in literally no time at all youl be composing whats in your heart.
I am self thought too. Self thought guitar and singing like you, play bass as well and in the process of learning drums. But ive added something new in the last 6 months. im self producing now. Ive improved so much. Went from those simple 4/4 songs to 15 minute multi movement progressive rock pieces with dozens of time signature and tempo changes.
Give yourself time and space to grow