JJ, too timid?

Typical Hand for me. Am I too timid?

100nl Pokerstars. I'm in small blind($0.50) with JJ.

MP(unknown) raises to $3, I call, everyone else folds.

Pot: $7
Flop: 8 8 4

I bet $3, trying to see were I stand. MP Raises to $7.
I call, thinking that I show some strength with my call on this flop.

Pot: $21
Turn: 2

I check, he bets $15, I fold

What do you think?