First question: considering the fact that you have a limited amount of time/resources to allocate, how will moving into Android (for example) effect your efforts on the iPhone platform?

Second question: is there some reason to believe that the growth path on Android (for example) would be significantly better than you've experienced on the iPhone?

Without knowing the answer to those questions, I can only surmise that the fact that you had to turn down 3 large campaigns because you couldn't support the volume required suggests that your number one priority ought to be building up the volume to the required level before diversifying onto other platforms.

According to you initial plan, how did you intend to get traction?

My answer, at its core is: unless you are talking about pivoting (which is different than "expanding into new markets"), the time to consider secondary markets is after you've got momentum in your first.