I have been told that I have very porous hair. It was dyed very blonde and now is having a hard time holding on to darker color. I have been using color conserving shampoo from Aveda and leave in conditioners, but is there anything else I can do?

Also, this was the first time I got a foil job instead of all over color. My hair was at a 10 level and they used bleach highlights with level 7 lowlights on foils. There is a hard line where my roots were though. It has only been a week since my coloring and there was a pretty defined line when I left the salon (my roots are just under an inch long right now, medium brown). Is this normal for the first coloring and will it get better? I feel so gross right now with the roots but I don't want to color again this soon...

Please help.