To be in control is being able to influence outcomes well in advance making the end result predictable. Not being 100% of the time in control is one of the realities of the modern CTO.
Sometimes you will be faced with issues that are outside of your control (migrating a live service which 1000s of customers use from an old supplier to the new one, for example).
A way to mitigate the unknowns is to map out outcomes and plan of action for each. At minimum set up a reliable support network (develop relationships with supliers, say). You can always scream later.