I'd recommend aiming for these two SR kamihime, which you should be able to obtain without whaling (one from an event that's coming soon, the other from Gatcha):
http://xn--hckqz0e9cygq471ahu9b.xn--...81%8B%EF%BC%BD
http://神姫プロジェクト.攻略wiki.com/index.php...83%86%E3%83%97
One of them provides an attack debuff, while the other provides a type B ATK/DEF debuff. Sub one or both of them in for your current SRs. That'd let you stick with Andromeda for healing.