Estábamos sirviendo would be the answer for the nosotros form in the imperfect progressive. For future reference, you should check out the Spanish Dict online, it has all of the verbs in every form and tense :)
1. I have to order a new cookbook today.
2. I have to go to a conference with some colleagues.
3. I should go see my patient with diabetes.
4. Today, Monday, I can see more patients.
dam how many do you need me to do but when is this due
