Am I just a terrible developer?

I'm not trying to be click-bait-y. Please listen to my story and give me some feedback.

I'm sitting here right now, 30min from the first interview I've had since I graduated. Knees weak, palms are sweaty.

I would say my history as a software developer (web) is not a great one. I entered University under an Engineering degree at the age of 18. Failed a bunch of subjects, altered majors several times and ended up graduating with a Software Engineering degree. Trouble was, there weren't nearly enough programming subjects in the five year degree. Perhaps about four taught you basic programming and about another four that, well, they were programming based and but you were basically expected to know how to program.

It took me nearly 8 years to graduate the degree (working, part-time and all that) and I somehow found myself in a graduate software developer position in a small business of about 5-10 developers. Being a grad, I was thrown into the mix fixing and patching code (Java/JSP).

After beating on that drum for 2.5 years, I found myself at another position in another organisation. This time, the dev team was even smaller, 5 developers tops. I was forced to learn things for myself. For the first time I was forced to build web applications from scratch and learnt a tonne of stuff. Fast forward another 3 years to today. I'm sitting, waiting, 15 mins from my coding challenge.

I've noticed alot of these are testing me on basic things like array manipulation. Sorting algorithms. Big O notation. Things I never touched as a student or a junior.

I can build web apps and apis from scratch. Test them. But I struggle to do simple array manipulation.

I feel like a fraud. There's holes in my knowledge everywhere, I realise.

I'm freaking out and I'm wondering if anyone else is in the same position as me.

Time's up. Interview's starting.

Get back to me.

RRRREEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE.