curious19

I'm 19 years old and have thin hair due to a case of trichotillomania. luckily, i still have enough hair that i'm not too bad off but for a 19 year old, it's not in great shape. I also noticed some hair on my pillow recently which i wasn't a fan of. I'm more interested in preventing more hair loss than regrowing hair, but it would be nice to gel my hair up and have things look just a bit thicker than it is. 1. Can rogaine or propecia, or any minoxidil product have side effects on my hair growth if i started and then stopped taking it? 2. What are some good shampoos to use? the top three seem to be nioxin, nizoral, and revita. 3. Any other tips to keep the hair from thinning any further or possibly making it thicker?