Seems adding two colors to represent a specific group changes the universal theme of the rainbow flag of being inclusive to all regardless of anything. Additionally the flag represents states of mind not groupings of people.
Red = Life
Orange = Healing
Yellow = Sunlight
Green = Nature
Indigo = Serenity
Violet = Spirit
Regardless, the LGBT movement has seen many a symbol during the years and I’m sure will see many more iterations.
Myself, I’ve always related to the rainbow flag the best as it is seen in nature, everyday life, makes millions of colors and by those virtues instills that being gay is a normal product of life.
Nonetheless, Be Proud of who you are and if that means creating a symbol of that, then by all means do so.