Congrats! I suggest you get a lengha (skirt top thing with a dupatta) that is white and has a lot of beads on it. It would be fancy enough to go with both types of weddings. Or if you want wear one red bengali dress (modified to be more modest) to one event or half of the event and then change into the white gown. I've seen both done and it seems to keep both families happy.
I'll try to find some pictures if you like, but it's probably best to go shopping to find what is available in your area.
Thanks. I would really appreciate some pictures, cause the store that he is going to have me go look in is in nyc, and that will be like not too many days before the wedding, and that is like 3 months away inshallah. So yes I would appreciate some examples to keep in mind. Thank you.