there is a large genetic component to who gets depression. It’s mostly inherited like my schizophrenia or bad eyesight or asthma. So it’s an extra card we are dealt at birth and not our fault at all
That simply isn't true about depression and I don't think it's helpful to OP as it takes away her autonomy. She's down because of a relationship break up and putting too much pressure on herself regarding her career.
OP - take it from someone who is more than twice your age, you have plenty of time to make a fulfilling life for yourself. Ditch the brain fog inducing ADs and start doing yoga with Adrienne on YouTube, join the gym, do couch to 5k, join a walking group, Parkrun - get your body healthy and you'll start to feel more positive.
Look at Dr Mark Williams Mindfulness videos on YouTube. These are science based exercises to help you retrain your brain to stop negative thoughts overwhelming you.
I'd forget about "grad jobs" and look at entry level jobs in, say, the Civil Service, NHS, University sector, Housing and build a career from there
The Civil Service are recruiting all over the country so there's an opportunity to move away from your hometown if you wish. Manchester or Newcastle are vibrant cities so maybe try them rather than London.
If you've got friends, then get out with them but avoid alcohol for the time being. Are there some gigs you fancy, theatre, exhibitions? Go!
Plan some weekends away - alone if need be. Take your kindle loaded with engrossing books. Subscribe to Audible. And book some holidays. You wanted to travel, you don't need to take a year out, instead a week here, 10 days there and you can have some fabulous experiences.
And ... make sure you do the yoga and practise mindfulness so that when you start to feel overwhelmed (and you will - you're human!) you will have the tools within yourself to calm and reboot (sorry if that sounds like woo but it's true).
Honestly, OP, I'm excited for you.
All the best.