Explain to me what standing heat looks like in a gilt(vulva, activity of the gilt,etc) and when do I breed her after I see standing heat?

my gilt was swollen then a day or so later she would stand still when you put weight on her back. She never total locked up but she stand longer than she would on a normal day. Also she had a big attitude change. Would not eat very much and she always eats every last bite. But they should lock up when u put weight on there back. After she first stands breed after 12 hours then again in 12-18 hours. Hope that helps.