Wedding Weight Loss

Hi ladies! I'm currently looking for some tips and even some of your own experiences. Let me give you a run down. Currently I weigh in at about 340 (I'm sure that I've gained more since I was last weighed). My wedding is set for November 10th, 2018. I know it's possible for me to lose 30 pounds before then but would it be safe for me to lose 50? Would it be possible to lose more? If not id be fine losing 30-50 and continue to work to get the weight off after our wedding. Also I plan to go for my dress fitting some time in February. How will my weight loss affect the way I'm sized for my dress? I want to look and feel beautiful. Your advice and any thoughts and encouragement is greatly appreciated!