Her current reactions are very likely to be the result of being your carer. It's too much for one person to be both fulltime carer and partner. She needs breaks from you - and lots of them.
I suggest you find another carer so that your girlfriend can get a job. The time apart while she works will do you both good. Hopefully she's also got hobbies and friends which don't involve you either. In short, just make sure you're not living in each other's pockets.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.