losing my mind.

ive just discovered im expecting baby number 3 im only 20 and craping myself i always thought of expanding our family but now its happening i do not know what to do my youngest is only 10 months old im scared i wont have any time with her my oldest is in school but how do other mothers cope im married and we work so money isnt a problem and we have room i just didn't expect it to happen so soon.