At my undergrad, almost everyone took 16 credits, or 4 classes, per semester. I don't know how many credits your 5 classes are but I would really try to stay close to 16.
And 2 science classes per semester is enough for your freshman year. If you find that is too easy, you can always take 3 science classes the next year, but you really want to get a good gpa your freshman year, because it will barely move from that later on.
I would wait to take physics till at least your sophomore year, and take an easy class instead. And if you do wind up taking 3 science classes per semester, I think you would finish your major requirements your junior year (I only had 16 bio classes required for a bio major, and 2 were the intro class and the seminar class, really easy). I actually was in the top 10% of my high school class, and I went to a really competitive college, and found that taking two science classes per semester was challenging, especially because hardly any of the classes related to optometry or even humans.