It is time to move out. At 25 you need to be having your own life, your own space, and to detach from your parent’s influence. It is overdue. If you were 14 this would be a very different situation — and your parents would have a lot more need to influence and guide your life. But you are a fully-grown woman and you can’t afford (for you emotional well-being) to stay at home. You need a plan to leave. I’m suggesting three stages:
The first is to foster the cat so you are free to make the move when you are ready. I think you’ve hit on a very good idea in putting her into the care of someone else while you get your own life squared away.
Moving in with your boyfriend temporarily is a good second step to consider. Stop paying to live at home when there is nothing but aggravation and a lack of gratitude. Testing out how to live together is a good experiment for your independence from your mother and stepfather, and sampling how it will be with your boyfriend.
Finally, if your boyfriend doesn’t want to live together until after he is out of the Air Force, your plan of getting out doesn’t change. Now you find the coworker and ignore you mother and stepfather if they “flip out.” Stop putting your life on hold to try and please them, make them happy, or keep them from getting upset. This is your life and the struggle to find your own way is important.
This third step is necessary not only if your boyfriend doesn’t want to live together now, but also because he’ll be in the Air Force for a while and you’ll want to be independent from your parents. You may need to find a roommate and work extra time to afford to be independent, but it is worth the effort. Living with parents who do not let you become the adult you need to be isn’t healthy. As much as your boyfriend is a catalyst for you getting out of the house the goal is for you to get out not necessarily only to live with him.
In psychology the process you are going through is known as individuation. It means that you are beginning to recognize and differentiate who you are by making efforts to get your own needs met.