You suffer from depression
Depression is something that is toxic not just for your brain, but for your overall health and performance. It sucks out all your enthusiasm and replaces it with negative thoughts and self-loathing. With such thoughts, one is bound to not care about what one puts into their body.
Your thyroid
There is a reason why doctors stress the importance of proper functioning of the thyroid. It plays a very important part in our bodies and any malfunctioning of this gland must not be overlooked. If your thyroid is underactive (hypothyroidism), your metabolic rate would be slowed down, making you put on weight. Getting your thyroid checked regularly can save you from developing such a condition.
Your medications
If you have been doing everything right to shed a couple of pounds and notice no difference, your medications could be the culprit. A lot of them come with side-effects, which could take the form of increased appetite, lower your metabolic rate, etc. Discuss this with your doctor and see if you can substitute your current ones for any alternatives.