If you are skipping days using your bilevel, then you are undoing any good the device is doing for you.
I assume you have seen your doctor over the pain in your chest and shortness of breath. This may be due to your diagnosis of COPD and the effects of not using your BiLevel. Plus you may simply be using the wrong type of machine.
To answer your question, I've never missed a day of Cpap use...Not to say I haven't been tempted, but knowing how bad I'd feel the next day keeps me using it.
So going back to your first sentence "Some nights it's hard for me to sleep with my bipap." Can you be more specific? What is it your feeling and what bothers you?
Your profile tells us very little. What pressure setting are you using? What is your AHI reading and the breakdown of such? Mostly Obstructives, Hypopneas, clear airway?
Are you able to download the
OSCAR software? Follow the links in my signature line for guidance and post results here in this thread.
Your settings may not be set right for you and someone can help you after seeing some data.