A supplement that is very effective for improving hair growth is silica. A specific brand I've tried myself (and other people here) is Kal's Super Silica Plus with MSM.

They say it takes 3 weeks to form a new habit but sometimes we can do it in less. If you make yourself post it notes and stick them where you will see them to remind you to take your supplements and massage your hair even just once a day, before you know it you'll get used to it.

This is only a suggestion but an alternative to pulling strands to measure new growth could be to put on a mild hair coloring (such as Colorsilk) in a slightly lighter or warmer shade than your own, that way the new growth would become immediately visible. By making only a small change you would not really cause damage to your hair (especially if you do regular DTs) and you could promptly return it to your natural color at any time with one brief re-application of a color similar to your own, once hair has been colored it only takes 5-10 mins. for permanent color to develop in the already treated hair.
2A/3A, medium length, layered, colored dark/medium ash blonde - "CGer" since April '02.

"Converting the 'curlskeptics' one curly head at a time..." HWHC