I need to get my teeth to look better in 3 days? Can I whiten them at home? (photos)

You can try and whiten your teeth at home and I would try crest white strips because they tend to do a good job.  When I look at your pictures I would definitely say that bulimia is evident.  The back surfaces of your teeth and for some of the teeth the top surfaces (from your picture) are showing a distinct yellow hue which signifies dentin.  Dentin is the layer of tooth under the enamel and in a bulimic patient this happens because the stomach acid from vomiting repetitively over time wears away the enamel.  In your case if you apply whitening gel to the teeth it may be sensitive or uncomfortable.  I would limit the whitening to the facial (front) surfaces of the teeth with strips or if you have whitening trays made only put a bit of gel on the front surface of the tray.  I think the bigger issue here is getting to your dentist to learn about how we can protect the teeth long term and of course seeking treatment for the bulimia first and foremost.