I took it for a while and no issues to speak of for me, however some report bubs can get v gassy which is often evidenced in greener than average explosive poo and obvious discomfort between feeds..all you can do is keep an eye on it and see if that happens to the two of you!
I came off it recently and have not seen drop in supply however my daughter (also around 14 weeks old!) it could be different for everyone!
Also highly recommend blessed thistle to boost supply, not one to be taking forever but it can be helpful to get your supply going.
There is a supplement by Herbs of Gold brand called breastfeeding support containing both, yellow and blue label on white plastic bottle from your health food shop, however a bit more exxy than just fenugreek.
You can also get blessed thistle separately from vitamin shops, it comes in a brown container white lid, natures way or something like that!
Good luck!