Thyroid issues??

Hannah

So I’ve gained about 20 pounds in the last 10 or so months. I’m not necessarily overweight, I’m 20yo, 5’3 and I’m at 145lbs. I stopped taking the pill (Lo Loestrin) in October because my doc said that pill has been known to cause weight gain/ make it difficult to lose weight. I was on the Nuvaring for 3 months and then stopped a few weeks ago to give my body a break from artificial hormones. I haven’t lost any weight even though I barely eat (I have NO appetite anymore) and I’m constantly exhausted even though I’m not doing a whole lot (I work maybe 8 hours a day). Could this be my thyroid? PCOS? Should I see a doctor?