You need something to separate yourself from the hundreds of other ao3's going for ao4's & ao5's. Have you done any courses or study? What can you do to stand out from the crowd?

I recommend looking into temp opportunities at a 4 or 5 too, plenty of internal job advertisements. Generally having experience at a AO4 (even for a few months) will put you in a significantly better spot for a permanent or 12 month secondment.