Personal trainer/fitness advice needed please! I'm a total beginner. Talk to me like I know nothing!

I think pilates would be ideal for you. You could do a class or do them from home on YouTube, I like blogilates on you tube.

Or you could contact a few PTs and just tell them what you have here along with asking them how much they charge and see what they suggest.

Also. Don’t go with the trainer from the gym who is a 17 year old lad who has no idea what it’s like to be a woman in her 40’s. Look around for a trainer who gets you and your lifestyle.

I’m a qualified personal trainer (though I don’t train anyone at the moment) and have weight trained for years, with a lot of CrossFit thrown in.

Dont even vaguely worry about getting ‘bulky’. Unless you are training for hours per day, eating a very specific diet and have excellent genes it won’t happen. I train multiple times per week, eat a specific diet and would love to be ‘bulky’ and just can’t even get close. It won’t happen to you.

Firstly, you need to find something you enjoy doing, so you can keep up with it. If that’s a personal trainer, then great. For me it’s CrossFit. If you can, try lots of things until you find that thing.

It’s so so so important that you start to build muscle now. Starting light, getting some good coaching, and building up is the way to do it with your knees and wrists. Don’t become the 70 year old who has lost all her muscle and can’t get off the toilet or out of the bath. Eating more protein will help build muscle.

All of that would be addressed by a decent personal trainer. If you don’t know anyone to get recommendations from, google trainers in your area, have a look at their websites and have a chat with them - explain your physical limitations and see what they say.
las an aside, squats are one of the best things for dodgy knees (voice of experience) as they strengthen quads and other muscles which stabilise the joint. Also anyone can do weight training, and women should as they age because it has huge benefits.
I’m 59, overweight with an arthritic knee, and have been seeing my trainer once a week for just over 2 years. She has a home studio which means less equipment but I prefer it. She specialises in women’s health and fitness. We do body weight exercises, kettlebells, dumbbells, bar weights, resistance bands, boxing… I love it. It’s one of the very last spends I’d get rid of if I was struggling with money. I’m stronger, more flexible and fitter and I’ve dropped nearly 3 dress sizes (I’ve addressed food and other exercise, but I wouldn’t have done any of it without my trainer getting me going).

Do you think it possible you have EDS?
maybe try aqua aerobics first?? I started with that.