hair growth, castor oil routine and what shampoo?!

Hi girls I know this has little to do with the traditional  eve talks but I need your help. So, I am almost 30 and  have noticed that my hair is starting to grow slower. It used to take me 3-5 months to grow from 2 to 5 inches and now it takes me 5 month to grow 1-2 inches :(. So am starting a Castor oil hair mask routine 1-2 a week to grow my hair faster and help it get healthier.  I have reviewed  this oil and have chosen that this is the best way to go for me. Now, I do wash my hair frequently, every other day. I used to wash it everyday but now got into the every other day routine for about a year straight and it's working for me. The goal was to wash it every third day but my hair gets too messy and dry that it is impossible not to look horrible. I want to complement my castor oil treatment with a good natural sulphate free shampoo to use every other day that would help me grow the hair and let it moisture do you guys have any suggestions for me?  Tks so much in advance!!