I'm so sorry to hear about the loss of your daughter - my heart goes out to you.
I would suggest that your pregnancy would be taken into account. Children who are in the care system are very vulnerable and having a baby or young child might meet that you are unable to meet the children's needs primarily. You'd also have to think of the impact on your baby - certainly for adoption, and I would assume for fostering they would want any natural children to be older.
They wouldn't necesarily assume that you were emotionally unstable because of the loss of your daughter - but they would want to know that you had had sufficient time to grieve and work through all of your emotions - as a foster carer you would experience loss when children moved on so they would need to examine your emotional attachments.
It might be that they ask for you to wait for five years or so til your next child is about 5 or so.