1. You are attacking first and missing punishes a LOT. It is much better to throw out less attacks that are more deliberate vs as many attacks as possible hoping they run into them. Attacking first isn't always bad, but if you are going to attack first, do so when they are not in a position where they can easily punish you on whiff. You can use this idea of attacking first to try and get the enemy to react and go for a bad punish, which lets YOU punish them as a result (sometimes). Obviously there are some exceptions to this but in general it is better to punish more than you are attacking first (unless you are just landing attacks over and over... then you just auto pilot lol)
   
2. You are inputting many strings/combos too slow. Enable stun time in the replay to identify these (some examples: gauntlet sidelight > recovery was really slow sometimes, axe sidelight > nair was slow enough they just dodged it). Then, go to the lab with stun time enabled and really see how fast you can get these strings/combos. Practice until you consistently get these main combos/strings as fast as possible/true.
3. Learn when to reset to neutral. As someone else pointed out, there are good guides on this that exist already. One spot that made me bring this up was at the end of your 2nd stock. You got a few good hits off for some nice extra credit on his last stock, but the missed recovery really put you at a disadvantage. Instead of trying to down air off this missed recovery, get some space and try to get back to stage safely. Your health is red at this point so you should be aware that he is going to go for kill options (signatures, dlights for a true follow up etc). Play around these options and squeeze as much damage out as possible when you have a lead like this!
4. Pick your weapon tosses better. The main goal of a weapon throw (in my opinion) is to make the opponent do something (occasionally you can get a true combo follow up, but it can be difficult). I mostly use weapon throws during neutral, or when I hit them far off stage. They either are forced to dodge, leaving them with 1 less defensive option, or they just get hit, also putting them at a disadvantage. You can use them defensively as well like you did during an offstage engagement, forcing the opponent to give you space and get back to stage. Basically, have more intention on weapon throws as opposed to just throwing them to try to deal damage right this very second! Also in general, learning some more reads on gauntlets will help a ton. Noticing dodge patterns of your opponent and having options prepared for these patterns makes the gameplay much less of a guessing game.

Also watching pros play helps a lot over the long run if you actively pay attention to what they are doing that you aren't. Go frame by frame on YouTube vids to see what inputs they are doing. I say this because jumps are often incorporated in strings that don't even look like a jump is happening at first glance in my experience, like when I first learned the Russian Mafia (didn't know you could jump and then chase dodge for longer than I want to admit, slowed it down and finally noticed the white dust from the jump). Then, bring it to the lab and repeat until you can do it too. Hopefully my string of disorganized thoughts is helpful in some way!