Ecg came back okay but still having chest pain anxiety and shortness of breath, what could this be?

"Chest pain" in a 25yo will usually originate from the entrance to the stomach (located just behind the heart) the chest wall or lungs. Consuming caffeine, nicotine, acid drinks or carbonated beverages will aggravate stomach related pain. If this pressing down below your breastbone hurts, this may be heartburn and but still worthy of an office visit.

An ecg will only rule out a heart attack, anything else from an arrhythmia to a panic attack remains possible, including lung, esophageal and musculoskeletal pathology. This is where proper follow up with your doc in the office is needed in trying to better delineate the cause of your symptoms.

It is not feasible to provide an opinion without additional history, physical examination may be some tests. It would be prudent to see your doctor to see if you may be depressed. Depression is treatable. Counter-intuitive as it may seem, exercise may help. Start with low intensity exercise such as walking and gradually increase the intensity as tolerated. Drink more water. Wish you good health!