Take a deep breath. Relax.
You're only in your first semester of freshman year. It's good that you're educating yourself and preparing yourself now, but don't worry so much! The MCAT is difficult, but you have plenty of time to study for it. Also, if you don't care about what degree you get, I would recommend sticking with Biochemistry. I was a biochem major and I got a lot of my pre-reqs for med school knocked out because they were also required for my degree (saved a lot of time and money). You don't need to have a science major to do well on the MCAT, but it does save time when studying for it because you'll have a lot of the background on the science topics. I would try and get as high of a GPA as possible and as high of an MCAT as possible. Always try to aim higher, that way you're not struggling to beat the avg stats. Aim for that 4.0 gpa, but don't freak out if you get a 3.7. That's way better than aiming for a 3.7 and end up getting a 3.3. Same with the MCAT.
Also, work on EC right now. Start having some long term ECs or shadowing set up, that'll way it'll be easier to ask for LOR (esp from a physician) later when you apply to med school.
Studying for the MCAT was hard work, but when you get to med school it's like you're studying for the MCAT all day..every day..for 2 years. The MCAT was hard but it's nothing like med school. And I can't even imagine what boards are going to be like! So don't let the MCAT freak you out! If you're already panicking and worried about the MCAT and you're only a freshman, you need to find a way to manage your stress, and fast. Many people drop out of med school due to not being able to manage their stress levels, and those are the people that went to college, took the MCAT, and made it to med school. So relax! Take things easy and enjoy college! It'll be the easiest 4 years you'll have (if you do decide to go down this path). Don't let the thought of the MCAT make you so nervous. Try your best and you'll be fine!