Thin hair and getting older please help!

I used to have thick hair. Had my son almost 4 years ago and it’s gone downhill since then. I’m 41 and pretty sure to be entering perimenopause. I don’t take a lot of time for things like going to the salon and don’t have tons of money I want to put into expensive products. I mostly just shower and let air dry because I don’t want to use heat too much. Also I used to dye it(at home) but don’t anymore. Although I probably should since the gray is officially getting out of control.

My hair is thinning, kind of frizzy, a combination of curly, wavy, but doesn’t have great all over volume. So it’s kind of flat on top and gets more volume and then the ends have thinned a lot. Length is almost mid back.

Advice please. Please! 🙏