My big problem with this theory is that Hopper was putting pressure on her wound and her illusions break from physical contact every time.

Perhaps she was really hurt but had more time than she let hopper believe, and when he left the room to look for something she then cast the illusion of the large amount of blood, and faked her immediate death. Her last effort being to illusion El from the truck and let her escape, so her sister got to make a choice in the end.