Jessikams, you have done a wonderful job dying your hair.
Suntiger, 18 months ago my hairdresser talked about putting some hair extensions into the front section of my hair (which had breakage due to too much heat styling) as she thought it would help thicken up my hair. As long as you have a good stylist who is experienced with extensions, I think you should be OK. My stylist does loads of extensions and wears them herself, so I would feel fine having them. Personally I have not given them a try, but use a protein treatment on my hair 2x week and have been heat styling my hair less - which over the last year has worked out well to stop breakage and improve my hair condition.