(easier to blame her than me haha)
Well sometimes it IS them

I used shields with DS2 , he was a lazy feeder & they just helped him get going, we weaned off them at about 8 weeks I think & went on to BF for 14mths.

DD2 was also a lazy feeder & then I had oedema in my breasts at day 4 PP. I wanted to try shields again & the hospital LCs advised against them, said they can reduce supply. They recommended bottles, she refused the breast & 4mths on I am fulltime expressing - just my experience - I would give the shields a go.
WRT supply, sounds like you have a good supply but if it is a worry you can always express a bit after a feed, just to make sure that they are getting stimulated.
I think shields can help too with large breasts, gives them something more defined to latch onto IYKWIM?