I think Ethan mentioned he was in Israel, it may be difficult to find or ship authentic batteries there. I've heard plenty of people ordering from fasttech with batteries and receiving authentic (FT does tend to be pretty good about "authentic" versus "styled.") Lists of reputable vendors who ship to Israel? IDK, you'd have to contact each one of them and see, but if FT will ship to your location, it's better than ebay. Don't buy off ebay, there are plenty of people there selling clones of all sorts as authentic and it's very hard to know until the product has arrived if it's authentic or not.... I bought off ebay once, and never again.
It is difficult when you live in a country that's hard to get good equipment to, so I'd check with some vendors to see if they'll ship to your location, if not, FT is probably your best option. I hope it works out for you, you can sometimes tell if the batteries you have now are authentic by checking what's on the wrap versus under the wrap, and if they are named something "odd" or not on Mooch's battery chart.
But batteries can be a bit tough, so good luck with it. It's possible that the batteries you have now are underpowered or not authentic, so I might hold on to the mod you have, and try again with authentic batteries to see if that changes your experience.
Good luck!
Anna