In a fit of ebay enthusiasm (given that all maternity wear in the shops this season is black or white and sensible) I bought this sundress - I didn't even really notice it was halterneck. I don't really do halterneck. It is really nice, but I'd like to wear it not only on the beach and it is really low at the front and really thin cotton. I could put T-shirt under it, but it is hot; a vest top looks weird; what do I do? Please?