Catherine, try a 124gr bullet first to see if the point of impact rises. Some pistols seem to have varying points of impact with certain bullet weights of designs. Also try starting at 10rds and walking out in 10yd increments just to gauge what the POI's are out to 45yds. This will give you a better idea if it's the ammunition, sights or a combination of both. This information gathered will be key in diagnosing the issue.

Please either shoot it off a rest or have another shooter try it as it sounds like something in your grip may be causing you to push the muzzle down at the moment of firing also try different ammo.