I did find my email with "Your e-ticket receipt" with all the info as to Avios points used and cash charged to my Cr Card. However the IATA # is 33992884. The amounts on my e-ticket agree with what I was told by a BA agent the "future travel voucher" is worth (the email on the Future Travel Voucher only have Vo #, no amount and an Expirtation date of Apr 2022). I guess I got an Offline Voucher. Very confusing.
Still do not see why BA cannot attach it somehow into one's BA Exec Acct. - at least for Avios points part.
Anyway, I will keep all documentation as reference for the future. Thanks so much everyone for helping me understand.