My assembled clips are 4 minutes long but my squence is 7 minutes long.
That doesn't make sense. The sequence length is determined solely by the clips in it. The only way a sequence can be seven minutes long is if you have at least one clip that goes out to the seven minute mark, so you may want to expand the sequence view to take a closer look.
Do'h -- 2 pass mode -- I need to learn more patience.