I have been in your shoes with the guessing game of what is normal range. When my DD was 2 weeks old and had completed the milestones of a 3 month old I concluded that the milestones were set so low for children that are borderline. I never considered it was my child that was off the charts. :P It wasn't until DD was turning 2 yrs that I came out of my denial.
Also in reference to the verbal strength and all of a sudden focusing in on numbers and math concepts... JMHO but I see pockets of interests and intensity. They get focused on something and that skill soars, be it math or science or whatever. We have had days of only interested in math with adding and subtraction, as well as fractions. When she is in this mode she hardly opens a book. Reading falls to the side. But she refocuses and is back into reading and words. I also have seen sliding in areas that are not of great interest at the moment. DD has known her letters since 9 mths and the sounds each letter makes since 15 months but when she is in math mode she can forget the sounds or just doesn't really care to answer the question. But when in her reading mode she is intense. If that makes sense. Just wanted to share that as you progress in case your DD slides ... I find it normal and further shows the intensity these kids have when something interests them.
