Is it possible for thin hair to ever get thicker?

So I heard that your hair grows at the same rate as it falls out keeping the amount of hair at a constant, so I'm guessing you dont notice a difference in thickness, just length over time?

However, after I had my hair cut after a bad dye incident I started getting extensions, this thinned my hair. I've stopped this now and now wear clip ins that wont thin or damage my hair.

However, I was wondering, if my earlier thory is true that your hair is at a constant, is it impossible for my hair to ever thicken? I treat it with great respect now and dont pull or tug unnecessarily to help stop hairs getting pulled out, but I'm afraid I'll never have thick hair ever again :(

Is it possible for thin hair to ever get thicker?

I have thin hair also" and the only way mine ever gets more thicker" is to wash it with a shampoo that with chemicals from the shampoo it appears thicker for 1day...Curling makes mine look thicker also" but these are the only two ways i know to do it natural.....