About how far through the game am I.

I've been using the Drangleic sword and shield since I picked them up. Are there any boss weapons I could get which would be an upgrade over this sword?

There's still a surprising amount left in the game; you're probably at what you could call the final third of the game. There's still some boss weapons and armour sets to collect too, including the Mirror Knight stuff and a giant mace though they all of course require a lot of strength/vitality.

It's going to depend on what your build is and really what you're looking for as move sets are concerned. Like @yummylee mentioned there are several upcoming. As well as some really cool options when you get closer to the end of the game. One of which is an ultra great sword which I'm convinced is similar to the demon's great axe from Dark Souls 1 as far as damage is concerned. Though I haven't gotten it up to +5 yet.

@vikingrk: There are lots of weapons that are on par or better with stuff you find in the early game, it depends heavily on your build, playstyle, and personal initiative to experiment with other weapons (the Halberd is better than the Drangleic sword for example, and you don't even have to kill a boss to get to it).

I've got 25str and 20dex right now. It never seemed worth going above the requirements to get the damage scaling. I like the move set, but I would mind trying some different stuff. Is there info out there yet about stats after upgrading weapons?