I am only 27 years old. When I was 8, my family and I were carbon monoxided and when I was pregnant with my first child I went into premature labor and was put on Mag Sulfite for 27 days. Since you're 27, the cause is probably stress. Stress and anxiety often interfere with memory. Other common causes of memory problems in people in their 20s include smoking marijuana , using other psychoactive drugs like Valium and its relatives, or drinking alcohol.
Memory loss is something to be concerned about.
But even with the history you mention, forgetting things is unlikely to be related to a brain disorder in someone your age. I'd like to see what happens if you try some relaxation techniques and eliminate any factors from your life that might be interfering with your memory. The most effective stress reduction technique I know is conscious regulation of breath. Here are instructions for a great breathing exercise. Regular aerobic exercise and yoga are also good ways to relax and relieve tension.