I actually deal with ranked anxiety every time I queue up for ranked! Fun fact, it's so bad that I tend to spend more time playing ranked on my other accounts vs my main because I tend to under perform on this account.
That said, I'm able to handle it to some degree and I'll walk you through what I had to do to better handle this and improve my mental in ranked games.
First steps first, you need to determine what's causing the anxiety. Are you stressed because something is on the line? Is it IRL factors contributing to the anxiety? Do you not like getting scolded? (as a jungler, I sympathize) For me, personally, I found that my anxiety kicks in when LP is on the line. This is specifically because I DESPERATELY want to climb the ladder to prove to myself that I'm good at the game.
Once you determine what's causing your anxiety, the next steps are to look for resolutions. In your case, since you've said it's mostly IRL factors, I'd suggest making sure that you've completed ALL necessary obligations before playing a game. Create a to-do list. Knock out your homework, clean up your room, do your laundry, etc. Afterwards, lay back and queue up while feeling good about yourself because you knocked out your to-do list.
But you're in the same boat as me; you want to grind but losing impacts that. This one's a toughie. What I've found is that I need to look for victories in my losses. That is, when I lose a game, I take a good, hard look at what caused the loss. Did I contribute to the loss? If I did, what can I do to prevent that from reoccurring in future games? I'll go as far as looking back at a replay until I figure out where the critical mistake was. Once I determine what the failure was, I do what I can to avoid making those same mistakes. Finding something of substance that I can improve on; that's a victory in my eyes, regardless of the game's outcome.
When it come's to your environment, do what you can to make yourself comfortable. I tend to wrap myself in like... 12 blankets, put on slippers, and listen to loud anime music at full volume while I play. It's what I refer to as "The Zone". Determine what your version of "The Zone" is and get into it whenever you go into ranked. It's ritualistic, almost, but it helps!
Outside of that, I've always found that an easy method of dealing with the ranked blues is finding a duo queue partner. Preferably someone who you're comfortable with. I have a habit of duoing with one of my IRL friends whenever I'm on tilt and, within a game or two, I tend to be back in my groove if I'm playing with someone that has confidence in me.
Anyways, I think that about sums it up. Ranked's a spooky place sometimes and you're not the only one who's dealing with it, friendo!
