Cushing's disease may be cyclical, so your cortisol won't always be high early in the morning (check the Cushings subreddit, you can also see/ask what bloodwork people had done and when). Besides, slightly high cortisol due to stress and/or not sleeping enough (sometimes the high cortisol from these issues can be more than just slightly high, but that's irrelevant in your case) and high cortisol due to something else are two different things, so if you have a weird unexplained symptom that does not respond to anything (such as weight gain), you should pursue answers, even if your cortisol was a little high.
High reverse T3 is due to high cortisol, which you probably know. I assume you had an ultrasound done. High cortisol can lead to higher TSH — and FT4 because cortisol lowers its conversion to fT3.