Am I Crazy?

Random Vent, trying to understand the possibility before validation.. So about 2 Weeks ago, my bf and I ended up going to the ER (hospital).. I had been feeling signs of vertigo for 3-4 days prior and that day it was UNBEARABLE...The doctor asked me if I could possibly be pregnant, I said "Possibly, but not likely" lol.. So they did a pregnancy test. Few moments later said he was going to do a routine CAT scan, seeing on how I have been so dizzy and everything with slight headaches & leaves the room.. My bf and I are talking about how long we'd be in there because those aren't simple tests.. The doctor comes back in about 20 min later and asks "you're the pregnant one right?".. We just look at each other and I respond "not that I know of..." he walks over to the nurse station, comes back and confirms, "yes ma'am, the test came back positive".. We're excited and happy, my bf cries..

Quick back story.. He had hodgkins lymphoma.. He did radiation and chemo, has 2 other children from his ex wife, but they told him that he probably wouldn't have anymore after treatment..

So anyway, we weren't convinced, we went out the next day and bought a hpt, it was positive... Still not convinced (lol), 2 days later another.. Still positive.. BRIGHT LINES Positive.. But.... With his history and us been together almost 5 years, is it strange I still don't believe it?

(I have a Dr appointment scheduled for next week and I'm impatient lol)

Really just looking for opinions.