I would hire a security consulting firm to do the work for you. This is not the kind of thing you can learn overnight, or even in a short to medium timeframe. C

I would hire a security consulting firm to do the work for you. This is not the kind of thing you can learn overnight, or even in a short to medium timeframe. Countless startups have experienced security teams and yet were still breached - just do a quick google search. It's unrealistic to think an inexperienced engineer can do better.