You are correct- Zoology, Ecology, etc. all require some math. Statistics, yes. Calculus, yes. Possibly others depending on the program. Try as hard as you can to get past these subjects- you need to understand them even if you don't use them much once you're out of school.
If you really can't do the math, consider a less academic program like the college Fish and Wildlife Technician program offered through Sir Sandford Fleming. While they don't focus much on reptiles in the program, I know some first rate reptile people who have gone through it. Not everyone needs (or wants) an academic degree, or plans to go on to do a Ph. D.!
Either way, jobs in the field are scarce, pay is typically low, and you can expect to bounce from contract to contract as job security is even lower. That is just the nature of things these days.
I'd agree strongly with your sister, though- it is important to find something to do which you enjoy!