I'm pretty deep in the game and I'm still losing Gwent games against pretty much everyone. I have no heroes, my strongest card is a 6, and I'm not finding any of them ANYWHERE. Is this some kind of bugged thing or am I just not going to the right places?

Gwent is such a hassle and It kinds pisses me off that my deck is keeping me from advancing one of the main quests now (looking for Junior).

I have the same problem. I think you just have to win games to get the best cards, basically.

Though, for that specific quest you can also just ask about Junior and then kill all the guards.

Eh.. I only get garbage cards from beating merchants and the like. 2 power cards etc. It does me little good, I gave up playing random merchants and innkeepers because it takes too long to win a game to get another 3 power card.

Had a look around the net and the best cards are picked up doing certain quests.

I had problems with Gwent initially, getting my butt handed to me by Stepjan in Oxenfurt. Eventually I gave up for a while until I bought all the cards available from vendors, including Skellige. Now I'm working through the players and quests in Velen and Novigrad. I cleaned out all the players outside of Novigrad, plus a few in the city with only 2 or 3 losses.

Now it's kinda fun. I'm still not very good, but I have decent cards, especially Northern Realms and Nilfgardian, and the AI is pretty bad.