Weaning tips

My baby girl is 21 months old and I'm still breastfeeding. I'm definitely ready to stop but she seems to be using my nipple as a comfort blanket or something. She drinks whole milk and 3 meals a day. She even drinking out of a cup now. She can have her cup in her hand and still want the breast. Ugh! When does this end? She's use to not having it when I go out of town. Longest has been a week. I know some professionals say wait until their ready but I need help.