So I picked the pet slot totem and it says you need a gold account to activate it right. So if I do a week long gold account then activate the totem and don't fill it within that week will I lose my pet space till next time I activate a gold account?

yes, you won't be able to create/adopt a pet in any way without a GA after the first 5.

No, you never lose pet slots once you buy/earn them with Loyalty Boxes. But you're only able to fill them with an active GA. So you could use the totem now and wait six months to buy a GA to fill it, you'll still have the slot.

Thanks!