The chances of having a second stroke depend a great deal on what caused the initial stroke. In someone your age, the usual causes of stroke are 1) a tear
in the artery, 2) an inborn problem with the arteries, 3) inborn heart disease - such as a hole in the heart, or 4) a clotting disorder.
I would make sure you see a stroke specialist. Seeing a general Neurologist may not be sufficient. A stroke specialist may have additional ideas and testing that was not considered.
That said, a fairly large number of people with stroke at a young age do not have an identifiable cause. Luckily, this group has a relatively low recurrence risk. It is the patients WITH an identifiable cause that are the most troubling, because they are more likely to have a recurrence. I cannot quote you an exact figure, but if you have been thoroughly examined (by a stroke physician) and no underlying cause has been found, you should have a very low recurrence risk.