@Lesserspottedbex welcome!
Size ..... as @Bigtitsbetty said are you really sure that's your current size? If you are a size 12 in everything/ the rest of your shape apart from your boobs then it's highly unlikely you are a size 38 band. You are probably using the + 4" on band size when measuring that women of our age all did cause we got measured in M&S.
I spent years in 36/38 DD/E bras wondering why the back rode up so high. Actually I was a 30/32 FF/G cup. Duh!!!! Being in the right bra size does make a difference. Check out the Irish Bra Lady on instagram or the 'A bra that fits' website measuring tool.
Will having 1KG removed off the front of your body make a difference ... hell yeah!!! I'm the same age/height/ dress size as you. My boobs were horribly saggy and not so dense. I had about 600gms in total removed. My boobs before literally hung off my body, I had to fish them out of my armpits when lying down. Now they are very much 'on' my body and I'm no longer conscious that I'm carrying two saggy sacks around in scaffolding bras.
Like you, my main fear was that I was going to have elective surgery for something that 'wasn't that bad'. But ... I hated, hated, hated them and had spent years wanting to be rid of them. In the end that was what tipped it for me. I just needed it done.
Yes it's a big op, recovery is different for everyone and things can go wrong. I certainly didn't have the initial euphoria that a lot of people have and it has taken me a while to feel comfortable with the new me. But, there's a reason this surgery has a 97% satisfaction rate. Do I regret it, no, not for a minute.
If you have more questions, then ask .. this thread and the original one has been brilliant and I've been so grateful for the support and advice here.
@Madagascary ... thanks for the link ... had a listen ... honestly I'm still in my post surgery compressions bras for the gym, I just can't be arsed finding something else yet!!!