Alright, I'm going to weigh in on this because I was exactly in your situation before.
Freshman year, I pulled a 3.0 both semesters in all my classes. No A's or C's, just straight Bs. First semester Sophomore year, I made it a goal to pull my grades up and really get it together. I don't really know what that meant at that time, because looking back I didn't really change anything with my study habits or my outlook on college. I took Chem 101 and Chem lab 101 along with a basic Biology course.. only to get a C+ in Chem lab and a B- in Chem 101. Another B in Biology.
By this point, I was at a 2.9 sGPA, 3.1oGPA, and a second semester sophomore who hasn't even taken Molecular, Chem 2, or even Orgo. Needless to say, I was pretty hopeless. During Christmas break, I realized that if I didn't get at least 1 A in my science courses, I was probably going to have to drop out of Dentistry and pursue something different. Rather than making the empty promise of "pulling it together" I took a long hard look at myself and asked myself the questions I didn't want to know the answer to. For example "How much quality time studying do you REALLY do?" "If you are diligent, why are you on your laptop during class?" I treated second semester sophomore year like it was my last one in college... and got a 3.7.
Flash forward to my senior year, I now have a 3.4/3.5 sGPA, a 3.5 oGPA, and have received multiple pre dec interviews. I'm not typing this story to buff myself up, as my case isn't particularly extraordinary. I'm letting you know that theres a way out.
One thing that relieved my exam stress was not cramming. Cramming killed my GPA, and it killed my happiness for those first 3 semesters. Study every day, even if its only for 30 minutes. Just like a competitive athlete doesn't train only before their event, why should you only study before the test? Once I started studying diligently 2-3 WEEKS out from an exam did I start to notice some tangible results. It doesn't have to be 4 hours every day for 3 weeks, but enough so that you're not feeling pressured to take the test once it gets there. I urge you to try it.
That being said, you won't be perfect right away once you figure it out. I still got plenty of B's in those subsequent semesters, and I still struggled a lot in some classes. It was a constant process of tweaking my strategies. What was important was that as the semesters went on, they were an improvement from the previous ones. That's what's important. Play it one semester at a time, and just try to 1 up the previous one. before you know it, you'll be pulling A's in everything and laughing at yourself for doubting your abilities.