I think you really have to think about what you really want and not be swayed by others.
This time 2 years ago I had very long dyed brown hair. I decided to stop dyeing, and slowly started losing length, not because I wanted shorter hair but just to speed the process up.
I then decided to ask the hairdresser for a bit of layering and shaping that would bring hair to medium shoulder length but she cut 4 inches off more than I asked so in effect I ended up with short grey hair.
To say I was not happy is an understatement. I am now starting to notice it growing back and planning to have it long again.
Some days I like the colour and some days I don't. Some days it makes me feel so drab and it's really affected by lighting, weather, what I wear etc.
I had nothing but compliments for it but I think that's partly because women are just so scared of doing it and admire my 'courage'. I also notice, nearly 2 years on, the people who compliment me are still colouring and bleaching their own hair ...
I realised at one point I was feeling horrible about it all the time and it really knocked my confidence. I felt like a totally differently person. Also, it seemed, overnight, people were treating me differently and not in a positive way. I got to the stage where I realised that, as much of a bind as it was to keep on top of the roots, at least I was a lot happier and more confident with my appearance the rest of the time because I felt like the real me.
Also, I realised it was getting to point I didn't care what colour it was as long it was A COLOUR rather than grey.
So at the moment I am just concentrating on growing it and will most probably have it coloured but I will never go back to dark hair again so it will be lighter, blonder shades which means I won't care about the roots showing and I will be able to go to salon every 3 months or so.
Someone once said to me 'have the hair that shows your personality' and I think that is so true. I understand the concerns about chemicals etc and that is a consideration but taking all that on board it's a price I'm willing to pay.
I won't be telling anyone when I'm due to have it coloured as I know I'll get a barrage of people telling me how lovely my hair is and don't do it but I've decided now.
So this brings me to the first point - think about what YOU want and what you can live with and be actually happy about on a day to day basis for the foreseeable.
Weigh up all the pros and cons and don't be swayed by other people. Good luck!