JJ, too timid?

Typical play from me. Am I too timid?

100nl Pokerstars. I'm in SB($0.50) and get JJ.

MP(unknown) raises to $3 and I call. Everyone else folds.
pot $7
flop: 8 8 4

I bet $3, I'm trying to see were I stand. MP Raises to $7
I feel this might still be a medium pair or AK, so I call.
With this flop I feel I show some strength with my call.
Pot: $21
turn: 2

I check, he bets $15 I fold

What do you think?