Mayorofarcadia
My name is Emma c:
It's not your shampoo, it's your water temp. They make color-tinted shampoos and conditioners for a reason (they have "color-safe" options as well, but not all of them are. Sulfates are the key problem.)
Anyhow. I dye mine red -- red molecules are the LARGEST so they strip out fast, so I totally understand your problem with pink. But pink is only semi-permanent so it's going to fade no matter what you do.
Wash it in cold water (preferably every 3 days, but more often obviously if your hair is the type to get oily/greasy fast) and you'll be fine.
Wash it in hot water and it "opens" the hair shafts (much like how hot water/steam opens your pores?) and that lets the color wash away.
Obviously cold showers suck, so just lean over your sink/bathtub to wash your hair in cold water if you really wanna preserve the color. It's your best bet. No need to sacrifice shampooing. c:
I've used "colour protecting" shampoos before but it's the lathering that strips it :c I also see what you mean about the water temp though! I'll try it next time :3