It sortof sounds like this class is going to end up as a warlock, but with more invocations to choose from... except that it won't have eldritch blast and it's invocations are going to be even less powerful than a warlock's. Plus, on the whole the class will probably be less flavorful as well.

What exactly is your end-goal in creating this class? It's a bit hard to give advice without knowing where you're going with this.