Back fat

I think the tape will cause the silloette to look odd, because it's honestly very flattering right now. The tape can sit funny on the back and crease under a dress and you don't want that.
I promise you look great! It's a very flattering dress.

If you hadn't said in your post what the problem was I wouldn't have even noticed. I think the dress looks great!

I think you look great! How are you wearing your hair? A veil and your hair done can help cover the area you feel self-conscious about.

Hair down* not done. sorry! 😆

My first thought too was "what back fat?" Anyway, one standard method of smoothing it down is having someone run their finger along the inside of it once you're dressed. I don't have any experience with it but I've read that repeatedly on bridal forums.

It's skin.... Everyone has skin!

I think its normal... I've seen brides of all sizes and they have some skin that sticks out back there with the dress cute/design like yours.. I think it is do to shoulder width.... some peoples shoulders are wider than the bust to back area. But I understand I would be aggrevated about it too... maybe a sheer cover I'm not sure what they are called a bolo or something..lol

It may just be that the dress needs to adjust. My sister had the same issue with her dress when she tried it on after alterations but for the day of the dress was perfect and no “back fat” was visible. This may be the case for your dress as well. I agree with other pp the dress looks great on you and not really noticeable unless you point it out