Please, nobody who isn't a cryptographer (to be clear: I'm not one either) should be arbitrarily inventing schemes of combining cryptographic primitives and hoping they're secure in production use cases.
We'd often be wrong in such hopes, regardless of how good the underlying primitives are.
We should listen to the experts in that regard, and preferably use higher-level libraries written by the experts when performing common crypto operations. This stuff is easy to get wrong.