Saw Palmetto might help. Try the 160mg tablets twice daily.
There are some good hair shampoos available which are supposed to remove the DHT which accumulates and blocks the hair follices from growing.
By the way don't be afraid to use Rogaine. I have been using it for the past five years or so when I first noticed some thinning. I won't say that it has grown any hair, but I have not lost any! And I only use it once per day (before bed). The recommendation on the bottle is twice per day.
I think my point is to start a "hair keep" regime immediately. Regrowing hair is proving to be quite difficult. Keeping what you have can be done if you act early.