So far. no one has answered your post, so I'll give you my layman's interpretation of the situation.
For interpreting my comments that follow, please refer to the document below:A Guide to the Histopathology Reporting of a Polypectomy https://www.rcpa.edu.au/getattachment/53d45991-f083-4639-99ab-8cc9f913c4b7/Guide-Polypectomy-local-resections-CR.aspx
In my opinion, you are confusing the word "tubular" with the word "pedunculated". Your two 5mm polyps were "sessile"
polyps. This means they were flat polyps. The other main kind of polyp is called "pedunculated".
The terms "sessile"and "pedunculated" are terms describing the overall appearance
of the whole polyp when viewed by the naked eye by the doctor doing the colonoscopy. In the document above, these are indicated under the category "Morphology" and are found in section G3.04 on Page 2 of the document.
The term "tubular", on the other hand, refers to the way the microscopic cells of the tumor look when viewed under the microscope by the pathologist. There are three main types of cell structure for an adenoma polyp, and they are listed under section S3.01. They are called, "tubular", "tubulovillous", and "villous". According to the pathologist, your two 5mm polyps were of type "tubular"
, which means that the cells, under the microscope, look like a collection of tubes instead of being round like normal cells. On the other hand, "Villous" polyp cells look like cauliflower and they spread out in all different directions. "Tubular" adenomas are rather slow-growing and may eventually turn into cancer after 10 years or so. "Villous" polyps, on the other hand, are faster growing and more aggressive -- but you don't have any "villous" polyps, so you don't have to worry that much.
As for the fragmented 5mm polyp, it might be due to the possibility that the flat polyp was found in a fold or crevice of the colon and had to be taken out in pieces. Suppose that the polyp was 5mm long and 4mm wide, and that the left 2mm were on the left fold of the colon and the right 2mm were on the right fold of the colon. Then when these two pieces are removed and placed end-to-end, they would measure 10mm. But this would be an incorrect way to reconstruct the fragmented polyp. But the pathologist doesn't know what the polyp looked like originally and doesn't have the details, so he can only guess. So he guesses that the three fragments came from one long, narrow polyp, but his guess was probably wrong, because the correct situation may have been one 5mm x 2 mm slice from the left half, one 5mm x 2mm slice from the right half, and a smaller 3mm slice dug out from the gutter or the root of the crevice. The pathologist doesn't really know because all he knows is that he received 3 fragments each of a certain size. He doesn't know how these three fragments should be arranged to reconstruct the original polyp, so he just guesses that the original polyp was a long one consisting of 5mm+5mm+3mm = 13mm length. (This is all speculation on my part, but I think that this is probably the sort of thing that is going on. I think that only the doctor can tell how long the original polyp was because he was the only one to see it before it was cut up.) So, I don't think you have to worry much about the size of the polyp. I think it was probably 5mm as the doctor said.
As for the delay of 6 months in your followup colonoscopy, I don't think that it is all that important because your polyps were tubular adenomas, which are generally very slow growing. You will just have to wait to see what they find in the current colonoscopy.
If you want to read more about tubular adenoma polyps, you can read one of the many articles on that topic on the internet, e.g.Tubular adenoma of the colonhttps://www.dovemed.com/diseases-conditions/tubular-adenoma-of-the-colon/Colorectal polyps -- Definition, types, colonoscopic surveillance https://www.slideshare.net/dr_sidoun/colorectal-polyp