I like your situation with your sister, there's very few negatives to it. Clean your fish outdoors. Remember that time apart makes time together better - so the 45 minute distance from SO is ok. 400 a month is remarkably low. I'd stay right there and keep on with your long term financial plan. Getting that huge amount of student loan forgiven in 9 years is a huge windfall.

Advice from a 53 year old who has learned how fast a decade can go by.