胸がドキドキするわ。

胸がどきどきするわ。

I have butterflies in my stomach.

胸(むね)がドキドキするわ。

Mune ga dokidokisuru wa.

胸 (むね、むな)

chest; breast; breasts; bosom; bust; heart; lungs; stomach; heart; mind; feelings

が (が)

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

時々 (ときどき)

sometimes; at times

わ (わ)

indicates emotion or admiration; indicates emphasis; wah!; boo!

Readings: キョウ、むね、むな-

Meanings: bosom, breast, chest, heart, feelings