Which is Better For PCOS?

I am currently taking Metformin 2000mg a day (one in the morning and one in the afternoon) but sometimes I forget one of the dosage. So I spoke to my doctor and he suggested I get the Metformin ER (extended release). I just have to take it once a day. My concern is which is better for my PCOS? and What's the difference between them? Also, I am trying to conceive and I want to know which one has a better success rate? Sorry for to many questions in one. Thank you for your time and I hope to hear from you soon.