5mg not working

2.5mg seemed to be working but was starting to wear off so I upped it to 5mg on week 5. Since that, my appetite suppression seems to have gone altogether, feels like I'm constantly hungry on 5 mg compared to 2.5mg and just using a lot of willpower but the "food noise" has definitely came back since starting on 5mg. Is there a chance you could get a dud pen?