It is important not to let this go — don’t minimize it. There are several things that aren’t okay, like your father touching your butt, talking about your breasts, and spooning you after drinking. None of these behaviors are acceptable, and the fact that you list your age as 23, and have been concerned about this for some time, means it is time to say something.
Talk to your father directly about this. Let him know it bothers you and needs to end. At this point, you setting the boundaries is important. I’d also encourage you to talk to your sister and tell her to do the same. Start here and continue to reinforce this boundary with him. If it continues please talk to a therapist. The find help tab at the top of this page will help you find someone in your area.