too late to rush?

Honestly I don't think think many houses would take a senior. It just makes more sense to give a bid to someone who will be there for 3/4 years and will have the chance to take leadership roles around the house and will contribute more since they're there for longer. I know some juniors who got bids but I've never heard of a senior getting one

I've never heard of a senior pledging a sorority, let alone rushing. In all honesty, you probably might be released from rush. As someone above said, sororities prefer freshmen/sophomores because every girl they give a bid to is an investment... They would rather give a bid to a younger girl who will be there for 3-4 years rather than a girls while be there for 1-2 years. As I see it, you'd probably get released from recruitment even with your grades and involvement, or if anything maybe one or two lower ranked (not that tiers matter) houses might keep you.

But you need to see if sorority life is something you really want. Obviously, you've been financially held back, so is joining a sorority something just for your resume? Is it for the sisterhood? Is it for the social benefits? Just rush alone can get expensive so this is definitely something you should really think about.