Unassuming cue bid

Hi Bernard, we play 5 cd majors with weak NT so I opened the bidding with 1 club (better minor)as E. S bid 1D and W bid 1H. I wanted to show a bit of excitement so bid 2D (probably should have bid 1S). Partner went 2H thinking that my bid was an unassuming cue bid showing strength and support for hearts. I passed. Disaster but my question is whether my partner was right to interpret my 2D bd as an unassuming cue bid? I thought it applied only when partner opens and there is an overcall by the next player.