My husband used to visit the USA from Vancouver on ESTA about once a month without issue while his K1 was pending. Through both YVR pre-clearance and via land borders. Granted he was a perm resident in Canada at the time (Irish citizen/irish born) and only ever stayed 2-7 days at a time in the US.
I agree with other posters, might be safer to cut down a little on how long you're staying. Also bring documentation for ties to home. My husband always had his on hand but was never asked for it.