Nathaniel (1616-1644) is known to have had only two children. Some of the ones you listed are biologically impossible if you compare dates. Nathaniel was born in England, most likely Newport Pagnell. There were two other Potter immigrants (George and Robert) that came to RI around the same time but we have no documentation of a relationship between all of them. I do believe Robert was most likely an older brother to Nathaniel but until we have DNA studies it cannot be proven. There are a lot of fictitious genealogies for the various Potters that
arrived not just in RI but in New England in the 1600s and it looks like you found one. Nathaniel, the immigrant, was not born in Portsmouth in 1616 since it was not yet settled by Europeans. The Mayflower landed in 1620 so any dates for people of European ancestry born/married/died in New England prior to that are not accurate.
According to Massachusetts records accessed at NEHGS Stoughton was the son of Aaron and Hopestill (--) Potter, born 17 April 1725 in Dartmouth. Aaron was the son of your Samuel Potter. The Nathaniel you have as father to Stoughton is actually his uncle. I did not find a birth for Humphrey in the records but that may not mean anything other than that The 1800 census does show a Humphrey living in Dartmouth that appears the right age to be your Humphrey.
I have the Potter book but right now someone else is borrowing it so I cannot see if it carries your line down any more than what I have given you. I have to add that anything found in the book needs to be checked against primary sources because it has lots of errors and omissions and virtually no source documentation. That was pretty common in 1888 when the book was published but it has been tough to try to unravel some of the messes it created.
Donna Potter in RI (I descend from both sons of Nathaniel, but my primary Potter line and two others come down from Ichabod. I share the line for Nathaniel and Elizabeth Stokes but I descend from their daughter Mary via my paternal grandmother. All my other lines are interwoven with Shermans and all come down to my paternal grandfather.)