So I have a boa, I believe a BCI. According to previous owner he (or she, it's hard when previous owners don't even have their facts straight you know) is almost 3. He's a little over 5 feet long. I'm feeding him medium size rats every 2 weeks. So is this a normal size for this age, regardless of sex, and would it be ok if I moved the feedings to every 3 weeks?