I don't understand master games. I play too much blitz. Not enough OTB. I am terrible at chess. How do I plough on?

What games are you looking at?

"... [annotated games are] infinitely more useful than bare game scores. However, annotated games vary widely in quality. Some are excellent study material. Others are poor. But the most numerous fall into a third category - good-but-wrong-for-you. ... You want games with annotations that answer the questions that baffle you the most. ..." - GM Andrew Soltis (2010)

"..., you have to make a decision: have tons of fun playing blitz (without learning much), or be serious and play with longer time controls so you can actually think.

One isn't better than another. Having fun playing bullet is great stuff, while 3-0 and 5-0 are also ways to get your pulse pounding and blood pressure leaping off the charts. But will you become a good player? Most likely not.

Of course, you can do both (long and fast games), but I don’t recommend that right now. ..." - IM Jeremy Silman (June 9, 2016)

https://www.chess.com/article/view/longer-time-controls-are-more-instructive

Thanks @kindaspongey. Definitely helpful.

Well, what made you believe in yourself in the first place?

If one's hand passes through a table, I suppose one could doubt oneself like Patrick Swayze in Ghost or one could be like Dr. McCoy in The Tholian Web and doubt the table.

you dont

:troll

I started with the belief that I might get a little better.

i play chess as if my life depends on it, thats why im able to sacrifice my queen in move 3 and resign

seriously i am beginning to doubt that i ll ever be a gm

I don't believe in you.  Why should anyone else believe in you?  Are you familiar with the story "Peter Pan"?  There's a character, "Tinkerbell", whose continuing existence depends on the audience believing in her.  If I were the sole audience, Tinkerbell would be SOL.  Do I have the permission of a moderator of chess.com to explain in this forum what SOL means?

To annoy everyone: Carlsen, Firouzja, Karjakin, Nakamura, etc., all grew up playing TONS of blitz online, so it's not like too much blitz is a terrible thing if you balance it out with everything else.

We have entered a generation where you can literally track the progress of GMs in the making as they improve online: https://www.chess.com/stats/live/blitz/nihalsarin (click "All time" to see him go from a ~1800 patzer to the ~3000 blitz beast, ~2600 OTB). 

(Slightly irrelevant but worth putting out there)

Develop a study plan.  Memorize as many tactical motifs as possible: they help you see the board better.  You should do tactics problems, daily if possible even if it's only for 15 minutes, here or at places like chesstempo. And after solving, go back and tell yourself WHICH tactics were involved (then check the TAGS listed with the problem) and try to understand why it took so long to see them. You should slowly learn and be able to demonstrate every tactic on these interactive pages:

https://www.chess.com/article/view/chess-tactics--definitions-and-examples

https://chesstempo.com/tactical-motifs.html

As Martin Weteschnik says in his very excellent Chess Tactics from Scratch, 2^nd Ed. (c.2012) (pp. 16-23):  "Solving tactical puzzles without fully understanding the underlying mechanisms is not the most efficient way to learn. Instead you must first understand the elements of combinations....[the patterns] might look...trivial...but might turn up in complicated situations. Only if you know these simple patterns by heart will you be able to recognize them in very difficult situations. Have you ever lost due to an unforeseen [tactic]? [From such] games,...put the positions on a board and try to figure out why these [tactics] came as surprises.  Don't be satisfied with just being able to pinpoint the exact mistakes. Always try to understand the underlying causes of your defeats."

As far as game planning goes, I recommend Chessmaster Fred Wilson’s 4 principles from his excellent book Simple Attacking Plans where the 4 principles are demonstrated by 36 annotated games.  Considering these principles has often pointed me toward a solid plan:

I have come to believe there are only four essential, even primitive, concepts which you must learn and understand in order to play successful, attacking chess - Fred Wilson

1. In the opening, whenever justified, relentlessly attack the weak squares f7 or f2.
2. Most successful kingside attacks are directed against the squares h7 or h2, and they are often preceded by eliminating or driving off its defender. Corollary: most successful attacks require a long queen move.
3. If your opponent’s king is trapped in the center, make every reasonable effort to open and dominate the e-file, and sometimes the d-file also.
4. If possible, point all your pieces at your opponent’s king.

Believing in yourself will always keep you weak. Join the Zurich 1953 Cult and believe in The Higher Power!

there is so much in what makes a chess player , its not only knowing the moves , its you alone who will be tested in your ability by another , you may be cautious , you may be adventurous , but you will be you ,

there is nothing left to believe in ,in the heat of a chess game ,but yourself , granted you may have lines memorized by study to help you , but they can only help so much ,

I had a cat that would jump all the way up to the top of the refrigerator in order to steal a joint. She would take it under the bed, rip it to pieces, and eat the bits.

Catnip for REAL cats.

get a dog , your stash wont get catnapped

How do I continue to believe in myself.

Just know that no one else will. 

set very low goals and you probably won't be disappointed.