SpongeBob,
What if you never feel 100% "pain free"? Then what?
What if you always struggle with a measure of discomfort? What will you do?
You continue to seek reassurance that you'll be "pain free" one day. Just as your OS mentioned and we're trying to make you understand, no one can guarantee with one hundred percent certainty that a day will come when you'll suddenly be "pain free".
Your prosthetic hip will never match your natural hip. However, it is likely it will significantly improve your quality of life over what it was as your hip deteriorated. You were in need of the joint replacement, there is no going back, so now you need to adapt and accept your current situation with the hope it continues to improve.
You took a chance, as we all did, for a brighter future, but as we all realize, there is always the possibility of complications, or not attaining our desired result. There is nothing you can do to change the situation, so try to stop worrying about when / if you'll ever be "pain free" and begin living your life, within your current limitations, as your body continues to heal. In all honesty, some reading here may wish they were only dealing with a discomfort level of 2-3 as you described your situation, rather than their reality.
This may take a full year, but many notice improvement into their second and even third years after surgery. So I suggest you buckle up, since you're only 76 days in...it may be a long ride.