There's no harm in adding the fruit to primary; you'll just have one big layer of trub instead of two smaller ones. The amber won't really be ready to bottle for at least a week after you add the berries, so I'd go ahead and bottle the stout now anyway. It'll still age in the bottle, just not as quickly as in secondary. Unless its 8% alcohol or tastes harsh in some way, it probably desn't really need extended aging anyway.
Say no to intolerance: love gluten and lactose.