I'll second that, your teeth don't look bad at all. I've seen much worse, in my own mirror! And my dentist fixed them all up like new, and now I love them.
A full set of x-rays is the only thing that can really tell if you need fillings, etc. Gums can and do get better with a good cleaning, regular brushing and flossing. I barely brushed my teeth at all for about twenty years, and once I started brushing again and later flossing, combined with a couple of cleanings, my teeth and gums look WAY better. So, it can be done.
There's lot of options for your top teeth, if you want to straighten them. Your dentist can help you figure out what the options are.
Bottom line, it's never too late to get your teeth looking and feeling good again. And, we all think our teeth are the Worst Teeth In The World, but seriously, your teeth don't look bad or shocking at all.
Congratulations for getting an appointment scheduled, and good luck at your appointment next week. I know it feels like the end of the world, but dentistry these days is way kinder and gentler than it used to be. Once you get through the first exam you'll wonder what all the worry was about. Take care, and stop by the Journals here to read about other people's journeys. You're definitely not alone.