Ahh, the online check in system does have its days when it's not working perfectly, hence your seat numbers haven't been allocated. You will have your sequence number on your boarding pass, this is the number of people that have already checked in. I reccommend you go to the gate just before boarding and notify the staff that you are one of the few passengers the online check in system doesn't like, they will then look up your sequence number to see what seat you will have. But to really honest LBA-BFS usually has an average load of 80/90 passengers, as it has not worked you and your friend MAY not be sat together, but I would check with the staff. If you are not sat together when you get on board simply move to a free seat as there will be plenty of room.