can you share the date and flight number and cabin? There potentially some blocked seats if you are not Gold, the front row of CE and the 3 row behind the curtain in ET for example.
Unfortunately the BA seat map is not a good place to see how many available seats there are, expert flyer is better as it shows which seats are blocked rather and which are occupied. Ba shows both these types as unavailable. A free account on expert flyer will give you 5 searches a day.
If you share the info I will post a screen shot from Ef
and yes BA will seat you "together"