Ok, first off...
chill. Studying for Step 1 is pretty much the worst. It's normal to be stressed, and all of your classmates are feeling the pain. I think 2.5 wks is a considerable amount of time, during which you should be able to improve your score with diligent studying. What specialty are you shooting for? Review the NRMP match data here to get an idea of the kind of score you will need:
Charting Outcomes in the Match, 2014
Next, why do you think delaying is not an option? If you walk into your dean's office and tell them you need to delay your Step 1, they'll make it happen. Several people in my graduating class did it. This is no problem, unless you have some other reason you can't delay.
For pharm specifically, I used pharmcards by lange (you can get them on amazon) to memorize the minutiae. If you are having trouble with side effects specifically, think of the drug's mechanism of action. Many side effects are a direct consequence of the mechanism. For example, SSRI's commonly cause nausea/vomiting/diarrhea. That makes sense because the gut has serotonin receptors, that are stimulated by increasing amounts of serotonin, thus the patient pukes.
Another way to think about side effects is in terms of toxidromes. For example, TCA's are anticholinergic drugs. The anticholinergic toxidrome is "can't see, can't pee, can't spit, can't ****". Boom! Now you know the side effects of all the anticholinergic drugs like TCA's, benadryl, scopolamine, etc.