Janeywaney, everytime you talk to, work with, or just spend time with someone you teach them how you will allow them to treat you. She is only doing what you have allowed her to do in the past. Why should she change now?
I would not move just yet but you do need to communicate your displeasure and frustration to the BO.
Keep the conversation focused on you. By using I instead of you.
Such as I need to show this year and I am working extra..... I will go to college.... I need this from the BO.
Telling her SHE is the problem and SHE needs to change is going to put her on the defensive.
Acknowledge that she might be overworked but with college fast approaching YOU need more time to focus on other activities.
Never ever burn your bridges and always leave any place you board with a good reference and the ability to return if possible.
Good luck. Shalom