Cal-gal-
I can't answer why your hair growth is slowed but other members are doing an excellent job as always.
Having fine hair most of my life I have always researched ways to make hair healthier and recall reading through numerous sources that doing a 5 min scalp massage with a few drops of oil (olive, jajoba, almond etc.) prior to washing your hair will increase blood flow to your scalp therefore help with growth. I do the almond oil if a have a few extra minutes and I will say that it gives my hair a nice shine and it looks much healthier.
I have also heard that adding a few drops of Rosemary oil to your shampoo and to work it through your scalp well each time you wash your hair will help stimulate hair folicles. I tried it and it didn't do a thing for me so I just stick to the almond oil
Lastly, I think pepermint oil is supposed to stimulate the hair folices too.
Ok, I'm all adviced out....lol
Wishing you the very best.