Shorter cycles with Metformin?

Hi ladies - did anybody experience shorter cycles while on Metformin?

I'm usually pretty regular around 33 days cycles, but last one was 27 (never had one this short in years) so I'm wondering if it's the new norm with the medication, or if it was just a "one of".

The reason why I can't wait to see the next cycles is that I'm starting IVF and need to take Estrace (Estraditol) at the end of the current cycle and I'm worried I may start too late if we base the calculations on the longer cycles...