The straps of your bra provide the final 10% support for your breasts and link the cups to the back band. When positioned correctly, you should be able to place 2 fingers under the straps.
If the straps are too tight, they can indent the shoulders to the point they become painful. If they are too loose, they may slip off your shoulders. You should check your straps on a regular basis as they may come loose after your bra has been washed.
You should also bear in mind that even with the best fitting bra, there may be still be some indentation to the top of the shoulders. However, provided you are happy with all the other checks we have discussed and you are not in any discomfort, there shouldn't be any cause for concern.
If in doubt, drop us a message and one of our lingerie consultants will be in touch to assist you.