My hair is also thin after 2 babies, stress, other things. It got thicker for a while but the front never fully recovered.
I cut it all the time whenever something significantly distressing/disturbing occurs in my life. I love short hair (but everyone says I look horrible) just as much as long or more. I love the feel of it. It does grow faster with supplements, so when I wanted my hair short I stopped taking them. lol
Reached shoulders, then in late March, I hacked it off again. Since with long hair, people I know AND strangers, treat me more respectfully (noticeable difference), I'm gonna try to grow it.
The picture in my profile is a goal to remind me- from about 3 years ago.
What worked in the past (for sure because way more haircuts were needed than prior to taking these) was:
iron pills, fish oil (filtered type is best so you avoid mercury as much as possible), cacao powder with milk and honey (the cacao helped, i know it did due to the growth). I tried other things, but stopped them as they didn't really do anything noticeable.
My mom is a doctor and nutritionist and after baby she also had me taking vit D + made traditional 'health foods for new mothers' to try and help (she said thinning and hairfall can be a sign of worse problems, so health foods were essential). This is stuff like semolina flour toasted in butter, simmered in milk, with raisins and nuts... my hair grew quite long and less fallout, so she was right. Any fall-out was mainly from the front (above forehead, and sides), which may be down to hormones and drinking TONS of coffee daily (ridiculous amount)
Trying Iron pills (anemic), B complex liquid (sublingual - not for hair specifically but it will help that too - pills make me break out),
silica gel, MSM powder (<< just bought and tried yesterday).
also for food/drink i've been doing these things for my hair:
'snow fungus' (it's not gross, similar texture/taste as cartilage, supposed to be good for hair and health, Chinese new mothers have it)
electrolyte powder in water, fresh juices with aloe vera, nut milk with dates.
trying to reduce caffeine-- for about 1 week- I know drastic reduction of sugar and unhealthy fats will help hair growth/health, in many ways, but have not done so far
Things which are good for hair are generally good for health, so I didn't need to say the non-supplement part here.