He's right. You are 20 cards way over and it's killing your deck consistency.
Get rid of Threatening Roar. If you're worried about your opponent hitting you, run Battle Fader instead since direct attacks are what really matter. This will actually at least put a monster on your board and is a hand trap that can't be hit by Called by the Grave (which you should also be running 2 of to stop Ash Blossom, her friends, Maxx "C", and other discard hand traps).
If your deck pops off in the GY a lot, ditch MST in favor of Twin Twisters.
Get rid of Dark Hole. Lightning Storm and Raigeki are enough. Even with those, I'd say pick one or the other and replace one with Harpie's Feather Duster for backrow.
Ditch Blustering Winds. It's only spell speed 1 and 1000 atk/def doesn't justify neither being a brick in the hand nor advancing your board. That difference won't win you that many games. You already run dragons which hit hard as it is.
Get rid of Mirror Force. It's an appealing card with niche use, but most remotely meta decks go off in the GY. If you were to use this against Tri-Brigade for example, you would be dead the next turn.
Put 2 Dragon Shrine and 3 Allure of Darkness in to speed up your deck. You might want to experiment with Trade-In. One Dragon Ravine would be useful since many Red Eyes cards bring out each other from the GY.
Replace Bottomless with Solemn Strike. Strike will negate the setup entirely while Bottomless is slower and can be negated by some monsters you want to stop with it in the first place. Ash Blossom will also take care of what Bottomless does sooner if you use her correctly. Ring of Destruction is also outclassed by these. Basically you want to identify and stop the big plays outright as often as possible.
You want your deck to generally look like this.
Consistent and trying to do one task with very few outlying tech cards that don't fit into your win condition. My deck is designed to get a huge monster as fast as possible and kill you in 4 cards. Everything else is there to facilitate this or be
complimentary back up should something go wrong.
Staples to consider:
Gameceil the Sea Turtle Kaiju - Completely goes over monsters that cannot be destroyed by battle, card effects, targeting effects, and summoning negation. This will get rid of any monster that has locked you down unless another card denies tributes or summoning monsters with certain stats.
Infinite Impermanence - Can be a hand trap to stop a monster in it's tracks.
Nibiru the Primal Being - Punishes greedy players that special summon a lot in one turn.
Maxx "C" - Rewards you against greedy players that special summon a lot in one turn.
PSY-Framegear Gamma - Negates monster effects and destroys the monster if you're empty and gives temporary defense if you run the Driver with it. All for the cost of one card.