I have received a positive response from a regional publisher who specializes in this kind of material after submitting three stories of my memoir of growing up in an isolated community on the central coast of of British Columbia Canada in the 1950s and 1960s. He now wants to see my entire manuscript. In editing the stories, the irritating thing that keeps coming up for me now is that my spell-checker wants me to not use contractions. The writing style I'm using is a casual conversational style, as if I'm telling you a tale over a beer so I frequently write things like "I didn't know at the time that I wasn't allowed to take my grandfather's boat without permission." The spell checker then insists that I should be writing "did not" and "was not." It's a pain in the ***.
Ignore it. Contractions are fine in any genre or style. Encouraged, in fact, unless you're deliberately going full formal affectation.
Can you set the spell checker to ignore contractions? If not, just add "isn't" and "wasn't" to the personal dictionary and soldier on.