First off, keep positive. Not only to team mates, but to yourself. Looking for help is the proper route.
Generally I tend to break down Ranked Stats (I do this for myself as well. I'm wanting 3 in each Lane/Role with a 60% Win Rate and 2.25 KDA before I start looking to progress, for instance. I have a few Champions there, but not enough for my liking. This helps me know who I really have a grasp on so I can progress with a proper Pool instead of riding on 1-2 Champions.)
You don't really have a lot of Ranked Games, but some things stick out.
- Brand. Continue playing him in Ranked, and focus on Not Dying as much. You split 1/1, but you made a huge impact with an Average of 10 Kills and 12 Assists, the issue was giving 10.5 Deaths per Game. I'm sure some of them were well worth it, but at 10 K and 12 A you're rather strong, so 1 for 1 Trades at that point are a LOSS, as you are Stronger than who you are Trading Lives with. At this point, you've become to Valuable to your Team to Die for 1 Kill.
In other words, if you can CONTINUE with the KA on Brand, you can work him into a nice Hard Carry for yourself. And most will tell you a Hard Carry is how you climb (and I don't argue against that).
Die less, get a bit more CS out of him, but keep that INTELLIGENT Pressure.
- ADC. Hasn't been your lane, but there are some to continue working with IN RANKED (obviously, work with all of them in Normals and Customs).
Your Vayne Kills... but dies as much as she kills and doesn't offset that with Assists. So either find a way to lower the Deaths, or find a way to be more Effective in Team Fights (which will generally add to your Assists or Kills to over all improve the KDA). I say work on Team Fights, because I feel you may be far better at Dueling already than you are at Team Fighting with Vayne, but that's just by looking at Stats which means I could be completely wrong. I'm betting most of your Vayne Deaths are in 'Team Fights Gone Wrong', but feel free to correct that.
Your Caitlyn is balanced. Low Deaths is nice, but not much impact either. Remember to generally farm from Brush (more Head Shots) and Poke from Brush (more Head Shots). You have the best Range of any ADC, until Tristana outscales you with her Passive extending her Range. Use that to your advantage. Cait and Ashe are about the safest ADC's in the Game (Ashe has fallen some, as changes to her Kit has slightly hurt her Kiting). You can be MORE AGGRESSIVE than your Enemy, because you have about 100 Units of Range more than them to generally work with... and a .90 Caliber Net to get out with if in to deep.
Also with Cait, work on your .90 to Q Combo. The Q's Range is from where you ACTIVATED Q, not where you end up from the Net. So if you can do a fluid Net to Q, you'll get Full Range on the Q from your START POINT while still flying backwards AWAY from the Enemy.
Ashe is more of a Utility ADC, so it's not ALL about Kills with hers. You drop your Deaths by about 2 a Game, you'll find your Ashe Winning a good bit more. Work on setting up good engages, and work on her Ult. You get good with the Ult, you can pick up Early Leads by Ulting Mid for an Assist/Kill for some cheese Gold while holding CS in your own lane, and with an Engage Support (Bruam/Leona/Thresh) landing an Ult when you hit 6 can be a Free Kill. Try baiting aggressive Jungles under your Turret with R as well. Your Ult will end most Channels as well, so if Morg is Ulting you and you can't Flash out... Ult her.
- Support. I'm assuming your Malphite was Support. If Top, that's fine too. Your Malphite is pretty solid, keep at it. I'll look at Builds you've used with him, but simply Guides can help with that a lot. Morgana was very solid for you Season 5, been a bit rocky in Season 6 for you... what's different? Being able to identify the difference will allow you to adjust to it.
That's some Champion Specific for you.
Generally, always look to Ward, regardless of your Position. If you are comfortable and feel good calling shots, don't be afraid to communicate in Chat and with Pings. Don't put yourself into position to play Champions you aren't comfortable with yet in Ranked (I dove in at Pre-Season 4 with 16 Champs and no Tier 3 Runes... a LOT of my Picks where uncomfortable. I wasn't ready... only use Champs you are comfortable on).
Hope it helps!