If i had a small, undetected (by ct) pancreatic tumor 1.5yrs ago, and it was therefore untreated, would i likely have symptoms by now?

Not particularly: There are many non cancerous or other forms of pancreatic malignancy including islet cell tumors, carcinoid, lymphoma, angiomas etc. Carcinoma develops intraductally over a 15-20 yr period of time and when invading basement membrane to parenchyma is usually fatal within year unless dx by obstructive jaundice. Otherwise most other symptoms of mailgancy are rapidly associated with mets.