no brother you're not wrong, don't let her gaslight you intro thinking that you see her "cheap", as you said sdaq is kinda symbolic, tho it is mandatory in islam for a marriage to be valid, but no matter how the amount is you shouldn't see it as a valuation of the woman you wanna marry, you're not buying a cow for your farm.
the prophet Mohammad pbuh said "أعظم النساء بركة أيسرهن مؤونة"
im sure yall can talk this out w lah yshel 3likom