People are usually prescribed oxygen use at home once their sat level is below 90. You definitely need to see a pulmonologist as soon as possible. Not only does low )2 levels zap your energy, it can also damage your organs.
Yes, I think I might be concerned. You might consider another opinion with a pulmonologist as your chest clinic seems to have dropped the ball. Have you ever had pulmonary function tests (pft's)? Did they send you home on oxygen, I hope?