I intentionally left a 8cm gap between laminate and a wall because there was an uneven wood beam in the concrete along the wall. I had the same problem in another room and I just put laminate over the bump and seems OK, so I think leaving the gap was a mistake.
Is there any way to fill that gap so that it ends up being same level as the rest of the floor. Ideally without a transition piece that sticks out of the floor (like a t mold). For example, one solution would be to glue many 8cm short laminate planks and effectively lengthen the existing pieces. But I'm afraid it won't look nice and moreover some of the ends of the existing pieces are not perfectly straight as they were cut.