Welcome, HTram ! I appreciate you jumping right in, and the boldness to stick maps in your first THREE posts is worthy of a dollop of reputation. Well, a smidgen since that's all the rep I can dole out...

Pssst - if you've been working with RobA's tutorials he'd probably be pleased if you wound up routing rivers plausibly. If that lake there has two outflows, it's unlikely enough as to draw the attention of the River Police, and we can't have that. Not that they ever issue anything but polite warnings, mind you :-). Water takes the single lowest path on the way to the sea, with divisions only usual locally, or when the terrain is so flat that every way looks 'down', like the threading in a delta.

If you intend the apparent lake to be sea level, and the two connectors to be sea level channels, you'd get better plausibility by making them obviously irregular width, not the same even line of your well-behaved rivers. If you want to keep most of what you have, just break one of the connectors, into a seaward bit and a lakeward bit.

Yeah, 'have drawn maps forever' is a common background here. If you count playing army on paper, my first maps were probably around when I was six or seven. I dabbled in D&D in college, and that caused a regional map that morphed into a world map. 'Driven to improve by a game' ... matches my forays into digital cartography to support my geofiction habit. My chosen tool is Serif's PhotoPlus, and though it has masks, I haven't yet mastered them at all, so you're forging ahead where I've been too lazy to go :-). Anyway - you'll enjoy it here, with a bunch of like-minded mapaholics.