6 is alot??

So 5 children ages 10,9,7 years 2.5 years and 8month old. Was on the pill but now early pregnant. We have a terrible time with the 2.5 year old. He's under assessment. He screams all the time, can't be left with anyone, rigid with routine and always having meltdowns. Screams all through night. 8 month old still wakes every 1-2 hours and because how other one is this makes him nervy and he screams in fear.

I feel so so down I don't know if have another will work will cope etc