Foremilk...?

If you started pumping right away after birth, it would have been colostrum for several days up to even a week. Then it would have changed gradually to regular milk, some of which was likely to be foremilk and some of which was likely to be hind milk.

If you've got frozen colostrum, you probably want to work that through pretty soon. It's very specialized and has quite a strong laxative effect because it was intended to purge meconium from your baby's system right after birth. You probably want to cut it with fresh milk and use it sparingly so as not to have a diaper blow-out. Just a thought......