callen510, we're sort of hijacking poor klouise99's thread so it probably would have been best to start a NEW thread with your question. But with apologies to the OP....
The schedules on the link I previously included (https://www.sorrentoinsider.com) correspond with this one: https://www.naplesbayferry.com/en/t/sorrento/positano
As they're updated weekly, I tend to trust them. They do not include the SEREMAR cruises on the pdf included on your sorrentotourism: other than the organized "Sorrento Gold Cruise" and similar packages, they don't post daily ferry schedules on their own website, if they provide that service at all. Anyway, you have to contact them and that's enough to warn me off that service.
https://www.seremar.it
Alilauro's schedules on their website are reflected on those shown in my two links above.
http://www.alilauro.it/en/departures-and-rates
Go to departures/prices, click on "Select the wished trafficking" and choose departure/arrival ports from the dropdown.
Caremar and SNAV do not serve Positano or Amalfi:
https://shop.caremar.it/en/
https://www.snav.it/en/orari-e-tratte
NLG's website is refusing to come up.
Lucibello doesn't serve Sorrento but their posted Positano> Amalfi schedule matches those shown in the my two links above:
https://www.lucibello.it/en/positano-jet
Travelmar doesn't serve Sorrento but their Positano> Amalfi schedule also matches those shown in the my two links above:
https://www.travelmar.it/en/hours
So, the tall and short of the matter is that schedules on either sorrentoinsider and naplesbayferry are essentially comprehensive and show the options you have to work with, Seremar aside. Note that those schedules could change a bit depending on when in the fall you're traveling.