If she came into heat on January 14, she would most likely have concieved after the 21st. (Counting on my fingers.) That would make her delivery date on or around the 22 to 26th of march. Give or take a few days because you don't know for sure when she actually concieved.

If her vulva didn't return to normal size after her heat and the discharge is minimal, clear and odorless she's probably got a puppy or three in there. In the next week you'll be able to tell more by her appearance! Now would be the time to increase her daily feedings by 1/3, preferably by adding a mid day meal. It's also time to alert your vet and set up the whelping box.

If the discharge is colored or has an odor, she needs to seen by your vet ASAP.