I'm glad you decided to share what your FIL and sister thinks about your wedding date. But you forgot the most important person... Your husband! What does he think? Is he ok with waiting 1.5 years more to start his married life b/c you want nice weather for the wedding day?
P.S. I get that you have certain dreams when it comes to your wedding day. You should have made sure all these details were worked out BEFORE the nikah. At this point, in my opinion, it will be better for you to focus more on your marriage rather than choosing to live apart from your husband b/c of weather.
i think its not a big issue in having wedding in Aug'15.
I was having the same issue as my sis & jeej & his bhai bhabhi lives out of country. but we hv discussed with everyone & got a date in which everyone is available.
I also wanted to get married in a cold weather but now for me & Him, Our family is more important than weather :)
you have many options to get rid of that garmi... but you can't alternate your family presence :)
