If you didnt get at least a 20% pay raise and your boss dumped additional work on you then you are getting shafted.
I recommend looking up how to take leave (disability or family medical) or beginning a job search someplace else out of this place.
In mean time - just because you have more work doesnt mean there are more hours in the week.
SLOW DOWN.
Working faster and taking on more responsibilities wont be fairly compensated.
And ask your manager for specific prioritization every monday for the next 40 hours.
Ask for an update in the AM every day (did my priorities change?)
Keep a log.
You are not a charity - you dont do extra work for free - they are not a charity - they dont offer fair compensation for the new work they dumped on you.
If they dont like the speed at which things are getting done, let them know they can always hire more people.
And if there are skillsets you dont know that departing staff had? Request training- when management balks? Go to HR and tell them you are not getting the training you need to do your job.
This company su-ks.
Treat them like the menace they really are.