You don't mention what the issue is with Engagement Splits as they sound like exactly what you need here.
In the absence of engagement splits, you could roll your own, but you would need to add your data extension to an attribute group in order to use in a decision split. This is similar to Eliot's answer.
Create Data Extension - (DoubleOptIns)
Add Your Data Extension to Contact Model
Add your data extension to an Attribute Group in Audience Builder -> Contact Builder -> Data Designer. You would link the new data extension from Contact.ContactKey to you data extension's SubscriberKey field.
Create a new Query Activity in Journey Builder -> Automation Studio -> Activities. The SQL needed should be similar to this:
_Click WITH (NOLOCK)
LinkName = 'Double Optin Link' AND
IsUnique = 1
And the query should be set to Update the DoubleOptIn data extension:
Create a new Automation in the Overview tab of Automation Studio and add your newly created Query Activity. Schedule the Automation to run once per hour.
You should now be able to use your new data extension in your Journey Builder Decision Splits.