Can't seem to win Ranked with Leona (Plat 5 Support Main)

http://i.imgur.com/FH6SRu2.png

This isn't a rant thread, trust me. Rather, I would like to know a proper build that could help her be useful during this meta. When I say meta, I mean during this patch of Season 7.

You see, I have 600k mastery on her, and she got me to Plat last season, but this season, despite being in Plat- I can't seem to win games with her. Primary reason is champions like are very good at keeping their team alive, and with items like , it makes it very hard for her to contest. Then you have champions like who literally tear her apart with the insane magic damage, even during late game.

Then again, i've noticed that whenever I play a tank support ( , ect.) they too can't really compete. Is this to say they're entirely useless? Not at all, I have managed to do well but it feels like I have to play to have a better chance at winning, and that sucks.

I really do want to play Leona, and I feel if I had the right build + items, I could make her of use. Also yea, I am aware that she's mostly a stun bot that is good at engaging but sucks at disengage, and can't do much else other than tank and stun. So again, any feedback would be greatly appreciated.