vlookup with offset...issue

hello

i have a simply inquiry that i cant seem to tackle

i have 2 columns of data *see sample attached*

column A = weeks
column B = headcount

essentially my criteria is "looking for last week and give me headcount"

however....if the last week is not populated...i would like for it to take the data from the row above or last active row

can someone pls help?

i tried this but getting a ref error

=VLOOKUP($F$5,OFFSET($F$5,,,COUNTA($B$3:$C$33)-1,1),2,FALSE)

can someone pls help