Novella obstacles

Basically how many are required for one? Mine has at least three in it. Is that enough or does it need more? They are all of pretty good length as well.

My usual answer applies: you'll never know until you write it!

Three sounds like a good number, though. So does one and five and twelve and three. It all depends on the type of obstacles and how the characters react to them.

The only thing for it, really, is to get writing and figure it out. If it feels like you're running out of substance, then maybe it's not enough. But novellas can be as short and novellas can be long.