You can see how supportive and friendly this community is by the helpful reply of Doolhof.
I can see how proud you are of your daughter and her achievements a double degree and excellent grades means she worked very hard.
I am thinking that if she finished last year it has only been six months and she is trying to work out what she does next.Study is exhausting and a double degree would be at least 5 or 6 years, so that is a long time of hard study. She may just be tired .
Does your daughter have friends she is in contact with and sees regularly?
Has she been applying for jobs or further study?
Maybe there are not a lot of jobs available in your daughters area of expertise.
It is understandable that you are worried about but you have seen suggesting she needs help does not work. Yelling is something most parents do out of frustration but that makes the barriers go up , and communication even harder.
As mums we want the best for our children and we don't want to seem them struggling.
Your daughter may indeed need to see a doctor but it must be her decision. It is a balancing act as you don't want to antagonise her so much she wont tell you things but you also don't want to misread a cry for help. That is just my thought you may feel differently.
Going on the computer can be productive and informative, I am on the computer a bit, going on this forum.
I like Doolhof's idea of going on an outing somewhere and enjoy each other's company with no agenda. Maybe there is a place she likes to go.
Thanks again for sharing your story.