Welcome to Mayo Connect @dgulovsen, First try to focus on what you know, and not what your mind wants to race ahead to. I know that's not easy, but it will help to manage the waiting. Waiting for appointments, waiting for test results, waiting for even more appointments, etc. I am not a doctor or clinician. I do have lung cancer, and I have a non-cancerous 1 cm lung nodule that just won't go away.
Different types of scanners may pick up different details. From another post, it sounds like your first scan may not have been a CT. The two sets of images may be difficult to compare. Also, there is still a human reviewing the images and writing the report. A 2mm difference may be a difference in the radiologists' interpretation or the angle of the image.
When a doctor recommends a biopsy, they want to be sure they can pinpoint the exact area of the nodule. The last thing they want is an inconclusive biopsy result. As @mamajite mentioned, this is why many pulmonologists will often wait until a nodule is at least 1cm before performing a biopsy. They also don't want to put you through the procedure if the nodule may reduce on its own. Waiting isn't always a bad thing, some like to call it 'active surveillance', so we can feel a little better about it.

Did your pulmonologist order the CT? Have you spoken with that office for their recommended next steps? It may help to have them call in a referral to Yale if that is where you want to continue your care.