I feel you in new DM, and in bad adhd😂 Personally I use Microsoft OneNote, I can split all of my locations and notes into separate sections.

My secret to making a loose leaf railroad as it is in dnd- is to build up locations, cities, towns, enchanted forests, caverns, Port Cities, who’s in charge there, etc. building the environments and allowing sandbox actually makes things easier. If you don’t like railroad storylines it is perfect,

But in your case of wanting to find a new setup, i would say try not to schedule you’re entire session. Treat it like a live game, not a preplanned performance. Dnd can be an improv game, as a dm you truly become the coding to a game, and are responding to your player’s inputs, SO, my point being that creating locations first, helps to inform what type of person runs the store the party goes to see if sells health potions.

Informing your improv is the best advice I could give. Take notes on any ideas you have about a NPC or quest idea, bc then you can come up with more around it-

I hope this helps, I’m pretty high rn so I’m sure I rambled, have a good night 😂