Bra help needed

[cashmerecardigans]

Would one of the lovely bra ladies be able to advise? I did the bra intervention a while back, changing from a 34E to 30G or GG depending on brand. Whilst it's been great for my shape, I've noticed recently I have dark lines where the straps run down and the same under my arms. I'm wondering if this means the bra is too tight?
I also have a real issue with excess fat overhanging the bra towards my back, which means I can no longer wear strappy tops as it just looks awful.
Can anyone help? I don't think I've changed size particularly and am not spilling out of the cups.
I'm helpfully on holiday so can't measure myself, but wearing a bikini has made me notice the marks properly so I do need to do something when I get back.

It sounds strange but strap marks can be a sign that your band is too loose, not too tight.

If the band is too loose, then it is not supporting your bust and so the straps are doing all the work.

If I were you, I'd look at a smaller band and maybe checking out a Balconette style bra as they are built to support your breasts from underneath and should take the pressure off the straps better.