I went through the images again and I got worried, extremely worried, because it seems like it has grown. I don't think quite as much as the radiologists say but it has grown after all. Of course there is a chance that the CT just so has happened to have taken picture in sequence so that looks like it has grown, but I'm skeptical. The length from base/pleura has been following:

1/3/2023 3.84
5/4/2023 3.95
8/22/2023 3.58
11/27/2023 4.35
2/27/2024 5.28
5/24/2024 5.65

Does anyone know how radiologists measure nodules? I read that it is the average of largest length and width. Width is measured perpendicularly to length.

Furthermore I read about tumors of pleura not being resectable, which made me fall off the edge again. Only reassuring thing is that whatever it is, it looks very much like the triangular one in this study:
"Management of Nodules Attached to the Costal Pleura at Low-Dose CT Screening for Lung Cancer"

You'll probably find it if you google it.

Reassuring part is that the study says all triangular nodules were benign. As in 0 were malignant in a study of ~900 participants. My nodule is almost in the same spot as mine is. Mine is just above the third rib from the top, right side. Of course it shifts as I breathe but with my lungs full of air its about 2-2.5mm left of my nipple and about 4cm upwards. So not quite where my doctors initially told it was (close to sternum).

I decided not to go get my CEA measured again. I don't think it would change anything even if it had gone up again. Only thing it could do to me is make me more worried. I've been in shambles past month. Last two days were much more reassuring but today after I went looking at the images again I got worried again.

Although Mayo Clinic accepts self-translated texts, I decided to buy a translation. Hopefully it will be better quality than my own texts. I should get it by next tuesday so I can send it to Mayo. The Mayo staff has been incredibly pleasant so far.