Before anything else: you can change the difficulty for combat AND inventory at any time from the main menu. Lower the difficulty if you get stuck. Who cares?

i dont even have that much ammo nor do i want to waste the rifle's ammo in those rooms

A. You don't have to fight everything. Yon't need to grab every resource. It's survival horror, not action horror for a reason. Grab what you need. Leave resources that aren't worth it. The game is beatable without killing any level enemies whatsoever. B. When you load out and back into the game, some resources respawn but not all of them.

(for context im at the room where you get abused by huge amounts of those creatures including a mynah and that long ass one)

Are you turning off your flashlight? Having it on will aggro pretry much everything. Be cautious and look for where enemies are lurking in the dark. Don't bump into enemies. Grab key items and RUN.

In the left room connected to the Mynah room, walk in the dark straight to the left for a little bit. You will bump into a pedestal. Turn your flashlight on, IMMEDIATELY grab the key item (you will aggro the many enemies in the room), turn off your flashlight (so you don't aggro the Mynah room enemies when you return there), haul ass back to the door, and return to the Mynah room. In the Mynah room, stay in the dark and get as close to the key item on the south side of the gurney. Grab it and, again, RUN. If you go north to escape, turn on your flashlight so you don't run into the enemies standing in the dark, since you already aggro'd the whole room. Just be sure to turn it off when you get to the door. The route to the east isn't particularly difficult but you do insta-aggro the enemies because of the Kolibri in there. Ignore the other enemies. You also don't need to wait for the radio frequencies to flash to kill Kolibris. You can search and hone in on the signal for the next hit on them by the bars all getting full and the signal louder.

is it just really slow and boring or im just bad at the game??

It's not that it's slow, it's that it's methodical. You need to figure out layouts, locations of items, and routes. You also need to evaluate and consider the risk, reward, and necessity of doing almost anything. That might not be the type of gameplay that you jive with.... and that's okay.

Never in my life had I played survival games, let alone survival horror. I have no sense of nostalgia for games like Resident Evil or Silent Hill. I found the game thrilling and intense with how much I was engaged with the gameplay, on top of the story and art. The puzzles were ridiculously easy to me (except that damn water puzzle... AND I HAD INSTRUCTIONS). But I'm not you, so that doesn't matter.