GIMP :: Make GIF Using WMV File As Source

I'm trying to make a .gif file using a .wmv file as the source. It needs to be small, about 2 mb or less.

When I first finished the .gif (about 150 frames), the file was much too large. I resized it, used the "optimize" feature, and made it grayscale, but it's still too big.

Now I want to try cutting frames to make the file size smaller. How do I cut every other frame in my .gif?

Alternatively, is there any way to choose the number of frames I want in "extract videorange" (for ex: I want only 10 frames from mark 3:00 to 3:30)?