Hormonal imbalance?? I need advice

Im currently miscarrying for the 2nd time in a row. My doctor set up an appointment for June 12th to start testing me, see if there are any underlying issues. Has anyone gone through this?? What should I expect at this appointment? What do they typically test for?

Im nervous. I can easily get pregnant but can't stay pregnant past 5 weeks. I didn't have any sort of fertility issues up until I got 1 single depo shot last August (2018).

I don't know what to expect. Anyone have any experiences they can share on the topic? If it's a hormone imbalance, what can they do to help?

Thanks everyone