I would say depends. If youre f2p i wouldnt say its terrible. Im a little p2p and lvl 77 with about 32k. depends on how youre spending your coupons.

I think that's okayish, though I'm not sure how long you've been playing and how much you've paid so I can't be 100% sure.

how can i get stronger then?

At that level, I was around 26-27k, which is... meh for a F2P.

Though it's hard to know exactly the quickest way to get stronger since I have no idea what you're behind on. However, I've found that tactics, charms, and rainbow magatama are helpful in general, especially the first few levels of tactics.

If you're a new player, it's best to save coupons and spend on power as opposed to luxury things like ninja and such. It helps in the long run. Your power could use some improvement, and if you ever need to look up teams to suit you try using this-
http://*.qq.com/tool/huoying/mnq.htm

At that lv I was in the 40s and I'm a f2p

I'm lvl 76 with 33k+

I only spent $10 for the card that gives 50 coupons a day