Going back blonde hair question?

Okay, so, I'm naturally blonde/dirty blonde. Well a few years back I started changing it up. Red, black, brown. About 2 months ago I had gotten a hair cut and did a color touch up which was brown. Well now I'm trying to go back blonde. So I would buy blonde hair dye and when I rinsed it out only my roots and a little bit on top would change color. So I went back and got john frieda hair color instead, thinking maybe it would be better, haven't used it yet though. How would I go about going full on blonde without bleaching it and I can't afford to go to a salon to get it done. So for the bottom half of my hair which still has the brown dye from a few months ago. Do I need to wait until it grows and have it cutt off or just leave the dye in a little longer?? Sorry if this made no sense. Any answers would help. Thanks :)