Can we keep bidding after our Negative Double?

North opens the bidding 1♦ and East overcalls 1♠. Sitting South, we have a lovely 6-card heart suit but only 6 high card points. We want to do something but aren't strong enough to bid hearts. Luckily, we have the negative double which will ask partner to bid one of the unbid suits. North now bids 2♣ and when it comes back to us, we must decide what to do.