Breastfeeding and boobs

Leah Margaret • 3 children to adore, and adding one more! My fiancé Craig and I are expecting pink bows on 06/04! 🎀
I have a question for the ladies that have breastfed their older children. This is my 4th, and last, child. I did breastfeed for a short month with my 2nd but mainly pumped as he was in the NICU for that month. (I would breastfeed him while I was there and pump for the times I wouldn't be). Unfortunately he became accustomed to the bottle nipple and when he was brought home would not latch and I hadn't pumped so I ended up switching to formula. 
Now this is my fiancé's first child and he has this thought that if I breastfeed I am going to have saggy boobs because of it. I try to explain to him that breastfeeding does not cause that; that it can actually help me lose weight faster, etc. But he is still addemently against it. I want to breastfeed our daughter, not only to save money but for the bonding experience, etc. I am normally a 32C when not pregnant. Currently I am (I believe), a 34D or 36C/D. I'm going out to get fitted and get new bras today. I really want him on board with breastfeed so I'm hoping some of you can shed some light on the connection between breastfeeding and "sagging boobs" IF there is one at all.
(I've always thought it's the pregnancy itself, with the breasts becoming larger and then going back to pre-pregnancy size that can cause dropping.) ALSO, do any of you know of any way to keep your breasts perky (exercise, certain food, certain clothing, etc). 
Anything I can tell him would be super helpful! 
⭐️Update:
I should mention that he's not against me doing what's best for our daughter. Nor has he been mean or pushy about the subject. Personally I just wanted to know everything about breastfeeding and how it relates to drooping. I've been having some bad self esteem and body issues over the past two years or so that has caused my depression to get bad. I believe he is worried about how I'll feel. We've actually talked about breast modification (breast reduction mostly but a loft also) due to the constant fluctuation in my bra size. I went from a 34B to a 34D and at one point was a 36DD. I have back problems among other things due to my boobs. Right now he's just concerned about how I will look in my own eyes. He could care less how I look. In fact he finds me most attractive in an oversized hoodie, with a pair of boxers thrown on under my 3X to big for me pink fleece owl pj pants, no makeup, etc.