cycle suddenly change ttcing

Hi ladies, have any of you experienced sudden changes in your cycle when ttcing.

This is our 2nd month and all of a sudden my regular 35 day cycle is long, currently CD 47. I have taken pregnancy tests and they are all negative.

The only thing i can pin it down to is possiby late ovulation as i received two 'peak' opks this cycle- one on CD18 and the other on CD 35 when AF was due. Im so confused i have never experienced this before.