Gathering amounts based on date for a monthly average

Given use of XL2007

E3: =COUNTIFS($A$3:$A$32,">="&$D3,$A$3:$A$32,"<"&EDATE($D3,1))
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F3: =SUMIFS($B$3:$B$32,$A$3:$A$32,">="&$D3,$A$3:$A$32,"<"&EDATE($D3,1))
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Note - neither of the above are backwards compatible with earlier versions - for earlier versions either use SUMPRODUCT or use a helper column to normalise date and revert to COUNTIF, SUMIF based around normalised date field.

EDIT:
just to add, I'm assuming you don't want to display all months - if you do you should just use a Pivot Table.