How do I find out what I recieved back per child

It isn't a set amount per child.  You can look at your tax return at each individual credit you received to see the amount of credit you got, but it is not going to break it down per child.  Each credit is calculated differently.  Earned Income Credit uses a table that is based on your earned income and filing status.  

The maximum amount of Earned Income Credit for Tax Year 2019 is:

• $6,557 with three or more qualifying children
• $5,828 with two qualifying children
• $3,526 with one qualifying child
• $529 with no qualifying children

If you want to see how the Child Tax Credit is calculated, check out the IRS Publication - the worksheet is on page 6.