Also, can you put off ovulation indefinitely in this scenario or must it still happen every month, just you choose when every month?
And yes, I agree that population would be lower, though maybe not quite as low as "small scattered tribes". But what I'm almsot certain of is that within the decade there would be a drug on the market that can force women to ovulate regularly which would be popular with old-fashioned people or abusive husbands desperate for an heir.
"War doesn't prove who's right, only who's left."
"Every saint has a past, every sinner has a future."