No, you do not need more subtests. The essay comp has no norms for six yos or first graders. (Norms begin with 3rd grade.). You could have sentence comp given, if you like, but it still won't give you a composite score. The composites you have are the equivalent of Total Reading and Total Math. The only other "Total" you could get would be Oral Language, which others more knowledgeable about DYS would have to comment on the value of.

...pronounced like the long vowel and first letter of the alphabet...