How to make my boobs look better in this dress

Jennifer
So I bought a dress online for Valentine's Day and of course I feel very wishy washy about it. I decided to go for a more my age type dress as I'm 21 and I usually buy very girly type dresses and wanted to try something more sexy this year. I love how it fits everywhere except around my chest. It's VERY low cut making it impossible to wear a bra, except when I don't wear a bra my boobs look super little (I have very wide boobs but they're flat af). The halter part of the dress also makes my boobs look saggy because the scoop and strap is so wide. I think the dress would look better if I had some cleavage going on so I was considering buying some of that boob tape. Does anyone know where I could get some? Or of a bra style I could try that might work with this dress. I have a halter bra but the scoop is so low the cups show. 
This is the dress with a bra but I had to tie it up tighter which made the fit of the dress overall a lot worse and I had to keep pulling the front up every 5 seconds because the cups kept showing