There's usually no way for anyone to guess what an un-named school's classes are like. It will even vary from instructor to instructor at the same school. Also, it really boils down to your work ethic -- can you sacrifice your personal time for the demands of these classes when everything goes wrong at one? However, some thoughts:
Biochemistry can be tough. There's a lot of material to cover, and you'll have to see how a course will address that. A 5-credit course? (that was mine) A 2 semester course? (typical, but you didn't call it Biochemistry I) Will you be left to your own ability to learn the whole book?
Analytical Chemistry w/ Lab can be very straightforward, or daunting, depending on the laboratory load. You'll be in a crowded space, sharing equipment. If things go slightly wrong, that compounds it, and just goes more wrong after that. It will be your time, to start over, if that's even allowed.
Physical chemistry is pretty math intensive. How that works for you is all up to you and your ability.
Pretty weird story tho' -- you have a degree, so you don't have a graduation deadline? So you're now majoring in chemistry? OK, working with that, Chemistry major with planetary science, so, Biochemistry, why that one?
If the answer is that you just love a challenge. Why wonder at all about the workload?