It does seem to have so many different variations, I think that's partly why doctors tend to brush us off to other health workers - they just don't know what to do! Some days I'm fine and have little pain and wobbliness, other days I can barely shower without having a nap afterwards and taking lots of painkillers. I'm not terribly hypermobile as an 8/9 but I'm mostly just outside the normal range of movement on the test rather than a contortionist, I also have no skin issues save a 50/50 chance of ugly scarring. It's really scary when you have no information on what to do or how or what the future will hold, the important and difficult thing is to get yourself some coping mechanisms, reading through the boards here and asking questions is a good starting place.
The advice to 'keep in shape' is good, but not terribly helpful - basically you need to see an experienced physiotherapist who is prepared to do some learning and take a patient-led approach. A physio will generally treat one problem by itself - I've encountered this a lot - but the ideal situation is a physio who will treat-as-seen and tackle issues as they arise while keeping the grand plan (core stability etc.) in mind. I'd seek advice from a physio before taking up any activity though, I got banned from yoga and pilates by my physio as I wasn't using my muscles properly, unbalanced my hips and put my SI out loads
she'll let me do it now I know how to deal with it though. You might also want to get your GP to refer you to a pain clinic or something similar, they can be good at advice when you've no idea what to do and very reassuring.
There will be good days and bad days but you'll still keep going, give us a shout if you need a bit of a pep talk