4 months and my breast milk drying up

J • Oh
Hi all you post pregnant beings,
I've given birth, obviously four months ago. 
I was breast feeding regularly, until I noticed that my milk supply was dropping. 
I tried everything to up the anti but nothing helped even expressing... this does in fact run in my family - my nana didn't even create milk!! 
Has anyone else ever found this happen to them also? 
Cheers