My two cents:
What's your definition of "struggling?" If it's the SDN defn, then you're not honoring your classes. This applies to ~90% of medical students. By that defn, I'm struggling. I make mid to low Bs, and haven't come close to honoring a class yet. If this is the case, then by all means, you're not struggling. Just continue trying to learn as much of the big picture as you can. You'll fill in the gaps as you go along.
On the other hand, if you are actually struggling to pass tests and classes, consider a few things that "most" people do to pass their first two years of medical school. Try going to class. (Most of SDN will disagree, but I actually get something out of it. Strangely, I get more distracted at my house than in the lecture hall). Review your ppts and notes at least 4-5x before the test. Read the textbooks recommended here and by your school. (Costanzo's Physiology, Baby Robbins, Katzung Pharm, etc.) Try talking it out with a class mate. It's easy to say that you understand something in your head as your reading it, it's entirely different to try to explain it to someone verbally. Lastly, get some exercise and dedicate some time each day to yourself. No one in their first two years needs to study 12 hours a day to pass. Exercise will make you more productive, you'll feel better about yourself, and you'll be healthier.