Just to say hope you're better soon
Flu is horrible
I know my supply definitely dropped when I had it when DD was 6mo - but she had it first and so her appetite dropped, so my supply dropped, and then when I got flu myself it dropped further, so I can definitely say that we've experienced that, but as Heidi said, you should find that all that feeding will help to build up your supply again. Actually since DD still didn't quite have her appetite back again when I got flu, I ended up doing a bit of extra pumping (may not have been necessary) to try to build it back up again - but is sounds like your LO is doing that work for you
Please just rest as much as you possibly can, I know that's hard to do in practice though
get well soon!