Likelyhood anal cancer would be missed in 34yr male after normal colonoscopy 1yr ago? (not even hemorrhoids seen at time of test) have them now tho.

Not big problem. Although hemorrhoids are an issue that can lead to anal cancer, they need to be very severe and longstanding and associated with a mass. Someone your age with a clear colonoscopy is still likely in the very low risk category for this cancer unless there is family history.
Unlikely. It is unlikely that you have anal cancer, but to be safe you should inform your primary care physician about your symptoms and undergo a physical examination.