I used to color my fine hair, partly because it made it thicker. Once your hair dye is grown out/cut off, you may find your hair back to being more fine, with less volume.

On shampoo days, consider first slathering conditioner on the dyed section of your hair to protect it. Then shampoo only your scalp, rinse everything, and then use a thick conditioner. Leave the conditioner on while you clean your body, etc. then rinse it. Using a leave-in conditioner will also help.

Finally, doing some deep treatments - applying a really rich moisturizing conditioner, then putting on a shower cap and blowing heat at it for a few minutes to warm up the conditioner and leaving it on for 20 mins or so - will help.

You've got lots of good ideas here. Be gentle with your hair and good luck.
2Poodles Southeast PA
fine, med porosity, normal elasticity
Currently using the following 2 - 3 x/week:
Living Proof Perfect Hair Day suphate-free Poo, cone-free CO and styling treatment, plus KCCC