Firstly don't panic, what's done is done and you can only do your best from now on. If you get the disease under control then you might never lose any teeth. I have had patients hang on to teeth with severe perio disease for their whole lives. If some teeth are loose you can consider things such a splinting further down the line.
The most important thing with perio disease is excellent oral hygiene. Brushing 2-3x a day every day, right up to your gums getting your brush between your gums and your teeth. I would recommend tepe brushes 2x a day as well. Sometimes disclosing tablets can be useful because we think we all think brush perfectly but everyone misses bits (including dentists!) and it shows up areas we miss.
Normal mouthwash is irrelevant really . Corsodyl (or chlorhexidine corsodyl is the brand) is the only mouthwash which is good, I would advice dipping your tepe brushes in corsodyl 1 x a day but not using is as a mouthwash regularly as it can stain your teeth. If you aren't bothered about staining use it as a mouthwash as it can be good.
The other thing to think about is if you smoke or if you are diabetic. Both of these can lead to perio disease.
After a course of deep cleaning it takes about 3 months to see any improvement or to see if it has been effective. You want to give your gums time to heal and re going back in just traumatises them in the healing process.
If you have excellent oral hygiene and regular deep cleans and you still have lots of active disease that's when you might consider other course of action, maybe even visiting a specialist (although this will be costly). Antibiotics are used very rarely, only when there is some kind of acute infection as they don't work long term.
Pus can be normal after a deep clean, there was probably pus their before but the clean has given it a route to drain. Pus itself can be fairly common or normal in people with periodontitis but you don't really want it. I wouldn't worry about it in that time frame but if it persists at the 3 month stage then I would be more concerned.
Don't worry op, you can get this under control. It will take work but it's definitely possible! There's always things that can be done and losing teeth is absolutely a last resort