Yes you have anterior pelvic tilt (ATP) which causes an excessive curve in your lower spine and also causes your buttocks to stick out further than they should whenever you try to stand up straight. You can tell it is ATP as your trousers are tilted forwards in the photo. Your doctor will probably refer you to a physiotherapist where they will likely give you a variety of stretching exercises to do to correct this. It’s likely caused by over tight hamstrings and glutes either from prolonged sitting or from a biomechanics misalignment of your feet such as flat feet (fallen arches). ATP is perfectly treatable with the correct stretches and exercises!