New to the game

Guys, we are talking 'bout nowadays. Not some decades/centuries ago where there was rarely any competition and much lower chess density.

That seniors that become XM finally had (X-1)M strength during their whole life. They didn't start from scratch, did they?

Personal note: I have been playing chess for 30 years. I have a good memory and I am not lacking talent. I devoted some 10.000h to chess amongs other things. I had trainers, was trainer myself and read say 50 books. My national rating index is "217" means 217 otb tournaments.
Starting at 16 achieving "CM" was somewhat the maximum I could gain. I think FM would have been possible but having/making a good job is also not bad. ;-)

Okay, now I've a question: I want to become a GM and I'm 13. I've been playing chess for like 2 and a half years. Is it possible for me?

@Sarg0n you started at 16? That's very impressive.
@CreativeThinking better to asked titled players, but if you are only 13 and have got this far in 2.5 years, it is possible.

@CreativeThinking you are rated about 1900 lichess rating in all variants and time controls. Is it possible for you to achieve about 2900 lichess rating in all variants and time controls? The challenge to become GM is about the same.

@CreativeThinking if you started playing at age 10.5 presumably rated 1500 and now at age 13 are rated 1900, that means a progress of 400 rating in 2.5 years. That means if you can sustain that same progress then you can reach GM strength in about 7.5 years.
The big if is sustaining progress. It usually gets harder to make progress the stronger you become. Key is to analyse your own lost games. Constantly work on your own weakest point.
Another issue is focus. All those variants and different time controls are distractions.

@rickrenegade Thanks for the positive comment!
@hangrad Well, I'll try my best to reach there, as I'm determined to become a GM. I only need 1000 rating points more...lol
@tpr At 10.5, I was like 1350. I always work hard to achieve something and get better, and also analyze the games that I lost to someone so that I can learn from my mistakes and never make those mistakes ever again. The only weak point that I have (I guess) is the conversion part. Many times I lose some of the games that were totally winning for me. The idea just doesn't spark in my mind for that moment (winning) only. I realize that after the game is over. I've been trying to get better at that particular weak point but nothing has improved so far. I don't know what to do. :(

It is quite common to lose concentration in a won position. You get bored that the opponent does not yet resign. Your thoughts start to wander off how beautifully you have played to get this clearly winning position. You start to play fast so as to clearly demonstrate how totally winning your position is. All this is recipe for a blunder and a loss. You have to stay focussed in a won position.

Another possibility is that you have some weakness in tactics or in endgame technique. Maybe you fail to see some tactical conversions. Maybe you miss conversions to winning endgames.

@CreativeThinking I have looked at an example.

Your opponent blunders a piece and you fail to take it.
You lose by blundering a rook.
You play too fast.

Yeah, I remember that game. I was very tired then, and wasn't in the mood to find a good move, or in general calculate anything. I was just playing too fast. But that's not an excuse, and I know that, that is an example of me losing for not concentrating. There are many games of mine like this one, I've to improve on that part.

@CreativeThinking What do you mean by competitive?

At first you will lose lots and then the glicko2 rating will get you to a bracket where you will be in a competitive range where you can win games, you just have to play enough games so you rating gets you where you can be competitive.

If you mean tournament competitive then you and i have missed the boat. Watch youtube vids there are some great channels. Try Jerry, he does YT channel called chessnetwork and the series is called Beginner to master.

Would you like a link? It WILL be very helpful. Also another series called "climbing the ratings ladder" is very good.

I am saying this as a complete beginner but the=ose channels have improved my game without doubt.