“Could I be having thyroid issues?”

I've been chatting with family and hypothyroidism seems to be what they think it could be. I am not sure and wanted to ask before jumping to any conclusions. I've noticed that I feel more lethargic the past few weeks and no matter how much sleep I get, I wake up feeling exhausted. My throat feels congested and my nose has been runny but those could be seasonal allergies and my friend had a cold recently. I've had the hardest trouble with losing weight. I've even opted to try the keto diet in hopes that I'll see some results. I make myself work out despite the exhaustion but even though it's been a month everything seems the same. I've been having sleep disturbances, though not every day, I'm often talking in my sleep (which I've never done). I feel sad or down quite frequently, like sudden mood swings, and it seems like anything can change my mood rather quickly. I was scared at first that it may be diabetes due to putting on some weight with no success of being able to take it off via exercise (went from 163 to 177). I know I'm getting older and maybe this is normal but I feel like even so I would've at least seen a pound or so come off at this point or stopped talking in my sleep due to increased physical activity. Any ideas on what this could be? Or am I just worried about nothing? I am turning 29 this year and wouldn't want to lose my military career due to an unforeseen medical issue. Also, headaches have been much more frequent but I lumped that in with allergies.