When I had my first period I didn't have my next one for another 2-3 months. It's because you're irregular and you probably will be for a while. It's completely normal so don't worry.
The white discharge is just your body cleaning your vagina, and the brown would most likely be your body also self cleaning your vagina it's brown because of old period blood.
I agree. All normal. :>) good luck
If you've had your periods for about a year, they won't be regular for a bit (Idk how to word it) other than that I'm not sure and yes it's normal to have white discharge on your underwear.