We were playing 2/1 and were NOT playing NFB. When PD rebid 3♣ I assumed that PD had a hand that was too weak to have bid 2♣ but too strong for a WJS to 3♣ whereas she assumed that 3♣ was new suit forcing by responder. My PD was also American in case this is played differently elsewhere. I told her that if she wants to force me after my 2♦ rebid on a sequence like this she has to cue bid 2♠.
Who's right?

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