Reporting for duty Ma'am! It's hard to get the exact colour you want when you consider that the base colour of your batch is always going to affect the overall outcome - hence red goes orange, green goes calf-poo colour, purple goes brown.
I use 'Trail by Fire' red mica and that's the best red I've ever used. Just. Don't. Spill. It! (Search the great red mica spill circa 2021).
It could be that you are not using enough? Or think about mixing colours to make them stronger. I often put a aqua blue in with my green ( it, combined with the 'yellow' of the base, makes the green stronger).
More recently I started using neons - and while they very bright on their own, they combine really well with micas to enhance colours that would otherwise be very weak - think yellows and greens.