PCOS question

Hey! So I have PCOS and I've been eating very healthily in the way that my doctor recommended. This summer I have lost 20 lbs. 
That said, today I was at a party and was completely mindlessly eating - lo and behold, I ate a whopping 160 grams of sugar in the form of various desserts. I don't usually go over 25-30g per day.  
I read somewhere that one bad meal can make you gain 2-3 lbs if you have PCOS . 
Is this the case? If I didn't go over my CALORIE total for the day, how much weight can I expect to gain? I'm super down about this. Note: I am not on any medications for PCOS 
TL;dr - I waaaay OD'd on sugar and am worries I am going to gain a ton of weight. 
Thank you so much for all your help!