Do I have the potential to be a GM one day??

This is just a bad opening, rumo, 7. c5 just equalises completely. Even if you go e5 and give white a chance, you still have much better winning chances with the standard variations rather than that one.

It's not "just a bad opening". After 7...c5 8.e5, black needs to know (or find) quite a few precise moves to reach equality. And even if he does, the position still contains a lot of life.

And yes, yes, other lines give white better chances of an advantage from an objective point of view. So what? Do you think Carlsen and Kramnik play the London because it promises an opening advantage?

I'm pretty sure Carlsen only plays d4 in fast time control games and yes, black does need to know exactly what to do in openings like those, so I guess it has a little bit of merit to it.

Your problem is that after 10.b4 you may find it difficult to really break open the queenside. White stands ready to answer b7-b5 with c4-c5 and a6-a5 with a2-a3. Targeting white's king is the right idea (that's the price white has to pay for his space advantage, he has to be very careful about his king), but once you play f5, your own king can come under fire, too. It's true that it is not all one-way (and clearly better position was perhaps a bit exaggerated), but after your knight is pushed back to d7, white has just the kind of position he is looking for in this line.

You may be pretty sure, but a quick look into any database will prove that you are also dead wrong. Just one example: http://www.chessgames.com/perl/chessgame?gid=1813667

So, Mr FM Rumo75, since you appear to know a lot more than some about Chess, well, obviously, you are an FM, how do you think I could improve.?

I don't know enough about you to tell you anything more specific than the usual: Study tactics, improve your board vision, play as many tournament games as you can afford and analyse them (especially the losses), ideally first with no engine assistance, so you can later analyse your analysis with help of an endine. Another advice would be: Forget about titles. Are you passionate about chess or do you just need a status symbol? 

Don't waste time trying to become a GM, try something more likely.  Like learning to fly.

Gee, that's not very encouraging 

I am currently 15.

http://www.plycount.com/players/USCF/14194968

I believe it is possible.

 It's probably unlikely but there's no reason why chess can't be a great hobby for life

You will never know what you are capable of until you try. Period. Do not listen to anyone that says that you cannot do something. Start by joining a solid chess club, reading and going through https://www.amazon.com/Aron-Nimzowitsch-System-Century-3-2-2000/dp/B00HTJYPNS/ref=sr_1_6?s=books&ie=UTF8&qid=1477355596&sr=1-6&keywords=my+system+aron+nimzowitsch and also getting lessons from a highly rated player (preferrably a NM, IM, or GM), doing tactics on http://chesstempo.com/user-guide/en/blitzVersusStandard.html or on here, and playing chess every single day, especially with higher rated players who will tell you when you make a mistake and why it was a mistake. Don't expect to improve too quickly, embrace the learning process and journey and not the end result. Chess practice in real life >>>>>> online chess as well. Focus on one or two openings and learning the principles and tactics of chess until you are much higher rated and then you can focus on openings.

I think we are missing the point here. OP wants to go past 1200. That's not that difficult. Here's the secret - I know some of you are going to be pretty upset that I am giving it away so sorry.

The idea is a bit ingenious, so my require re-reading. Everyone starts at 1200 on this site. So, create 2 new accounts, and play one account with the other account. One of the accounts will have more than 1200. Here comes the important part - STOP PLAYING CHESS WITH THE ACCOUNT WHICH ONE. You will always be above 1200.

Does anybody know, I am broke, my parents are broke, I simply can't do what you suggest, i.e. Join a club, get lessons, etc. So, what can I do besides lose. By the way i am temporarily 1150😩

Then you cant be a GM.

There are a lot of free resources you can use.  The chess club of St. Louis publishes some very nice and instructive videos on youtube for you to use.  A lot of other channels publish good videos as well, just look around a bit.  Your school might have a chess club as well, if they do it would be a good idea to join them at least for other players to practice against.

How to reassess your chess by Jeremy Simlan is quite instructive as well, and if you do a google search for "how to reassess your chess pdf" who knows what you may find?

Not everything that can help you improve has to cost a lot! 

Try the chess.com tactics trainer.

There are also helpful youtube videos (I recommend the IChess Channel).

Analyze your games, practice :)

Hope this helps

Broke? I doubt it.

Still though, there are plenty of resources that are free :)

IChess.net has a nice youtube channel, as well as a free Newsletter.

Chess.com has many articles etc.