why my level is so unstable


Hi! My name is Lauren Goodkind and I'm a chess coach based in California. To help you beat him, I suggest several things:
1) Consider all checks and captures. Can you safely capture a piece? Do you have any good checks?
2) Ask, "If I move here, is it safe?" to avoid any silly mistakes
3) Take your time before moving and ask, "If I move here, where is he going to move?"
I hope this helps.

ugh tell me about it - so many times I'll play well and other times my rating will fall off a cliff. So what's up? Combination of reasons that might contribute actually!
a) The math in the rating system features a ton of variance based on how it is calculated. In practical terms, it means that it is normal to fluctuate rating a ton; besides, it is only an estimate - not an exact science. Rating doesn't take into account other factors like what openings you/opponent play, chess playstyles, or even how much experience/study one player has.
b) Human factors: we are not machines who play 1000-level chess EVERY game or 1500-level chess EVERY game (or whatever rating etc.). We are human and a ton of factors can make us play way better or way worse (usually worse lol) on any given day or chess session. Some factors might be, but by no means limited to:
-lack of sleep
-nutrition
-mood
-distractions
-level of nervousness
and many other reasons with various elements more present or more significant under various circumstances. For example, nutrition might matter a ton for OTB events where you play hours non-stop but might not be as significant in online blitz.
c) Sort of connected to the last two, but it is EXPECTED you will vary a ton (it isn't mentally easy to handle, but everyone goes through sooo many ups and downs in chess rating if they play any decent amount of games). Say you are actually rated 1000 on chess.com; some days you will be "in the flow" and play a 1500 player tough! Similarly, there will be days you feel fine, but struggle with a 500 player! Frustrating, but that is okay and certainly normal; in fact, I'd be suspicious if someone didn't have massive ups and downs in their rating stats/archive. The ratings are measures that you meet by reaching that level consistently. Given enough games (sample size) to stabilize rating, a 1500 player will play roughly 1500 level on average. If they begin to play better on average then their rating will go up. Too often (honest players unknowing how rating works or trolls calling attention) someone will claim they are x-rated in chess because they won a single game versus an x-rated player. Ooh look at me, I won versus a 2000 player in an online blitz game - so I must be 2000! That is cool, but you should only be 2000 if that was your normal - you get the idea.
In short, rating varies a ton and that is not only expected - it is human. The key is to try (I know it might not be easy when we all care about rating probably more than we should ) and not worry too much about rating numbers and focus more emphasis on learning and improving. If you learn and implement a lot into your chess, then your rating will catch up long-term

I second Kesoto,
Also remember sometimes when u learn new things such as new better tactics. It takes time to solidify. In other words you may not always know how to implement your learning. So enjoy the process!
Oh and if you get frustrated it will affect your game! It does mine.... : ))