Slip up

I made this slip from some gorgeous silk I bought in Melbourne, at Rathdowne Remnants. I used Simplicity 4352, a 1940s pattern, view 1.
It's not cut on the bias, but the instructions said a side opening was 'optional'. I was happy to find I could get it on without an opening. Unfortunately I had to unpick the side to get out of it, so I ended up having to put an invisible zip in. I can live with that.
The problem is, it's extremely unflattering on me. Perhaps due to not being cut on the bias, it clings rather than skims and is quite a horrible shape on. I persevered thinking that some stretch lace might make it prettier.
Ugh, all the lace did was make the sides gape horribly under the arms.
Sigh. It didn't take long to make, thankfully, and I have about 2.5 metres of the pretty green silk left, so if I can find a better slip pattern I will try again. Anybody have any tried and true bias cut slip patterns to recommend?