Hey man. I feel you. I have the exact same size lawn and am surrounded by maple and oak on all 4 sides.
The amount of leaves that I get is staggering and in no way can you mulch those in. I tried ut one year, I had sections of grass just matted down with leaves. Grass died, not possible basically.
Since I have trees on all sides, my aim is to usually push the leaves into the tree line.
First of all get a bigger mower. It will help ALOT. A timemasted with a bag AND a side discharge chute. The second is a walk behind blower (you did already) or a ginormous backpack.
Mostly what I do is follow this pattern and keep side discharging. Start in the middle and keep doing rectangles around the line, discharging to the sides. I know one side will end up near your house or something but keep a tarp there and bring it to the tree line. I start in the middle because I realized at one point its too much for my mower especially if it's wet (which it will be eventually). This is a rough drawing.
If you think you can't mow them because it's too much and need to bag them, blow them out on to a hard surface, driveway, walkway etc. Make some lines, mulch them first and then bag it.
Eventually I would advise you to save up for a much bigger mower with a bagging system. It's worth it.
Hope this helps.