Based on my experience, what can I do besides being an astronaut

I don't think there's much you can do as your experience and results tell two different tales. You went to a prestigious University but didn't achieve a grade that is reflective of the academic calibre expected of graduates. A lot of your experience was obtained whilst you were studying, where your final grade was probably of little relevance at the time. I think it maybe is best you are realistic with your expectations; you will not be getting into NASA with that grade. You can either try and do postgraduate course elsewhere, but bear in mind you'd need to achieve a Distinction, or apply for different jobs. Good luck!