[Everything] How many white walkers are left alive?

We've seen Sam kill an unarmed one before the baby scene. We only see 4 attacking the three eyed Raven, meera kills one. Jon then kills one in Hardhome. In the earlier episodes I counted 14 in the baby scene, 15 if you include the baby. So from my estimate assuming the baby has magically grown there are around 13 left alive. Thoughts?