Since you just replaced the sites, did you check your zero to make sure they didn't get knocked off during the match? If the sites are on then it would be nice to have someone watch you shoot and diagnose why you are having problems and do dry fire drills to correct the issue and reinforce with live fire. There are drills, advice and various products that might be of interest linked below:

Matt Burkett's website look under shooting tips


Rob Letham's Website, Look under ask Rob

Steve Anderson's Website
Kevin Schlier
Poconos, PA
www.brcv-gun.org

Whiskey for my men and beer for the horses.