Lightmap issue solved!!!
I had a problem with objects beeing way to shiny as well, and for some reason, fixing this also fixed the lightmap issue
When I tried to follow the bytehazard-tutorial I got an error when I used the mesh viewer so I didn't really get the chance to see if the tutorial worked.
However, this might have been obvious for most of you but the solution was too use "Photoshop" instead of "paint.net" to make my textures
And to every other unknowing person out there, the solution is:
- use photoshop as texture editing software
- make your alpha channel darker if your object is to shiny
- save as .dds, DXT5 - interpolated alpha
And a huge thanks to everyone who have helped solving the issue