Not sure I qualify as a hair color pro, but I'll give it a shot since I've been coloring my hair for almost 40 years and have been blonde, red (disaster) and all shades of brown.
Yes, definitely go to a salon next time because you are having trouble. The best advice I can give is not to dye the whole head. If you must dye the whole head, make a commitment only to dye the roots as they come in after that. You can't keep dying all your hair over and over - it is just too damaging.
Before you go in for your next dye job, use a heavy duty protein treatment. You can get it at any drugstore. I think one is called EmergenCee. Follow that (in the same shower) with a heavy duty conditioning treatment. Just plan to spend at least an hour between these two treatments. Boring, I know, but it will help.
Also, if you are bound and determined to have hair that is wildly different from your natural color and requires a stripping dye job, consider a wig instead. I'm serious. Most brown and dark brown hair has to be stripped to become blonde or have that blonde ombre effect. A professional is what you need.
Good luck going forward with this!
2/c and some 3A. Modified CG.
Highly porous. Color over grey.
Best 1st day method: Super Soaker
Conditioners: Curl Junkie Beauticurls Strengthening Conditioner,
Deep condish: Curl Junkie Curl Rehab
Stylers: Experimenting with cones & sulfates while the dews are high. Sometimes try roller sets - classic glamor but I prefer my curls.
Every day is a gift