Well, WaveRider is right that more info would be helpful, BUT, your symptoms (and the fact that you're worried enough to post about them) do mean *something* is wrong. There could be a lot of reasons for what's going on with your body.
In terms of diabetes, I was diagnosed when I started losing weight (I was thin already) and I couldn't eat enough to keep on weight, felt really tired after meals, and then when the uncontrollable thirst started, I knew I had to get to a doctor (I had known for a while something was wrong but kept putting off going to the doctor out of fear and wanting to pretend I was fine).
*I* now wish I had gone to get checked out before I finally did. Just trust me on this: knowing what is happening medically with your body is better than not knowing because then you can do something about it. Please see a doctor.
Yes. You don't provide enough information to get an expressive opinion.
Try to be more detailed in your post if you want the forum members to reply to your question.
Are you diabetic?
Are you on diabetic medication(s)?
How much did you weigh? When was this? How much do you weigh now?
What are your eating habits? Do you eat sugary sweets?
When was the last time you saw a doctor and had a blood test performed? What were the results?