It would be difficult for us to give you exact figures as to how possible it is. The possibly is not great, but it is there. Many people have HIV without realizing it. It is estimated that roughly 25% of people with HIV do not know that they have it. The only way to know is to take a test when the time comes.
Symptoms don't mean anything. Most people have no symptoms at all when they test positive. Some people have no symptoms at all for ten years. HIV is HIV, regardless of how you contract it. So the symptoms are the same regardless of how you contract it.
If she is willing, you could go with her and have her get tested. You would not show up as positive this soon even if you were infected, but she would, assuming she has been with her current partner for at least three months or more, has no other partners that she has been with for less than three months, and does not share needles. If she is negative, then you would know you probably are too. You could still test at the three month point to make sure if you want to, but at least you would not have to worry much in the meantime.
