Hi what a tricky situation.
This might sound a bit of a strange reply, but, it might help.
One of the things I read was that if you give a bf baby a bottle before they are three weeks old, they will always happily switch between breast and bottle. It may be that if you can express a feed to give lo occasionally in a bottle, this will genuinely help you because you won't be so tied to lo and may help mum see that you are being practical and addressing her concerns?
With regard to things that are different and suggestions, i find that replying "that is a good idea, I might try that" seems to work whether you intend ot try it or not.
Things to do, garden centres with cafes make good outings as lo can snooze in buggy and you can ususally find a quiet corner when she needs a feed.
Or maybe you could go with her to your local bf support group!