That's a beauty right there! Absolutely stunning, and what a pretty tail.
Below is my similar sized BC a Barranquilla, Colombian locale.
Same age. 5 year old male. 6.5' long.
The BCC above my picture is slightly shorter in length which is common. The BCC will tend to grow slower but end up larger in the end.
O/P did you ever read the book I recommended earlier in the thread?
I posted a bit of info here on the front end of the thread.
Feeding and husbandry play the biggest role in growth.
Eternally warm temps, with no seasonality will keep your animal's metabolism higher. It is NOT normal for a boa constrictor to eat year round, which is why in captivity you have to observe and practice some lighting, humidity and temperature variations during certain times of the year depending upon where you live.
2 large rats every 14 days is too much food IMO.
Read that book and look for Gus Rentfro's Facebook page.