Yikes. To get your GPA to a 3.5 which is the average, you need like 10 years of 4.0. Also, that dat score is pretty bad. Maybe science really isn't your strength? Every year you spent paying tuition as of now could of been spent earning money and the opportunity costs is going to be very high with no guarantee at the end. Have you thought about your other strengths? If it's math, go back to school for an accounting or engineer degree. What a 2.1 and 18AA shows is someone not good with the sciences. It's an uphill battle in every way. You can make it in the end but it's going to take time, energy, mental strength, and persistence. All when you can take like 3 years of courses and get a degree u can get a job in.