First off - if this had been my first map, I'd be a happy guy. So good job.
A couple of things:
That background is as bad as you say it is. This looks a lot like a Gimp clouds filter? I'd recommend just getting an actual old paper background, and using that instead. www.cgtextures.com has a bunch under Paper > Paper Old (or plain, or a few others). Just drop that in behind and it'll look a lot better.
Its not so much perspective that's off (the map is more a 3/4 view, so there's no real perspective at play). Instead, you have an inconsistent direction for up. This is super simple to fix going forward. Note that your whirlpool on the left is tilted from the horizontal? And it's tilted to the right. Now look at the jagged spikes in the land to the north - those are tilted left. That causes a clash (and slight sea-sickness) to the map. If you focus on keeping a consistent direction for up, this goes away. It's tricky with 3/4 view maps, but you'll pick it up quickly. It's a small fix.
Overall for these views there's a good trick to try - draw the map top down first. Just the coast lines, and ripples of water. Add other outlines (forest outlines, a river or two). Then get that into Gimp or photoshop, and scale vertically by 58%. You'll see what the map would actually look like in a 3/4 view. This will help give you a feel when you're trying to freehand the same view from scratch.
And forests? This one takes time. There are lots of styles to try. Here's my approach: http://www.fantasticmaps.com/2012/04...-draw-forests/
I find that not having a hard outline for forests on maps like this goes a long way to solving the problem you're seeing. But there's a ton of reference for forests. If nothing else, get a few aerial photos of forests and use them as reference when sketching.
http://www.citypictures.net/data/med...t_Colorado.jpg
http://ak8.picdn.net/shutterstock/vi...time-lapse.jpg
http://www.fs.fed.us/psw/ef/stanisla...st_shorter.jpg
http://www.traveltrack.in/Dimages/113.gif
https://upload.wikimedia.org/wikiped...eroad_edit.jpg