The tea looks ok though a May 2016 expiration date isn't accurate, it will definitely degrade before then. It looks fresh for now though. You can try using more to make it stronger.
Probably what the issue is is that the tea plants didn't get enough nitrogen while they were growing resulting in a bland taste. This is a common problem with organic green tea, though there are definitely some farmers that have figured it out and produce high quality organic tea.
I suggest trying another matchahttp://maiko.ne.jp/english/http://www.o-cha.com/http://www.zencha.net/
are where I usually buy my Japanese green tea. there's other websites worth checking out especially http://www.ippodo-tea.co.jp/en/
If you want a solid strong tasting matcha I think one of the best for beginners is this one: http://www.o-cha.com/uji-matcha-kiri.html
it's still one of my favourites
It's not organic though, I don't know how important that is to you.