If it's been fermenting for 2 weeks or more and the OG is 1008, just check again a couple of days later and if still 1008 then you can bottle it. Some people are ending up with a litre or so less than 5 litres, which means the boil is evaporating a lot away. Next time add half a litre to a litre to the sparge stage and hopefully you won't need to add so much water to the FV, if any. Maybe turn the heat down, as ful heat under 5 litres of wort may be more than needed.