So for your first game, they had a better late game team comp. Poppy can cc and screw up your assassins. Trist and Lux are already extremely safe with their long range and kiting. Morg can just Ult + snare anyone that dives too deep then use her Zhonyas. Meanwhile trynd can just 1v1 anyone with his ult. You needed to end this game as fast as possible to win it, but your team didn't kill enough turrets. The biggest issue I see, is that Kha'Zix got a double kill on Poppy and Trynd at around 10:30. Your top laner was not dead, so I imagine Teemo was present and this happened near top lane. Teemo and Kha'Zix should have been able to take a turret off of this, or at least Rift Herald. Instead nothing is accomplished and it takes over 3 more minutes to get the first objective (dragon) and another 4 minutes for the first turret, which Morgana manages to trade a turret at the same time. At this point Trynd starts doing what Trynd does best, and destroys all hopes of winning a head on fight for the rest of the game.
For the second game, the first major issue I see is that 27 minutes into the game your team gets 3 kills and does nothing with that. Prior to that you have done something with every multi kill. In fact, you get no objectives in this stretch that spans around 24 minutes until 37 minutes, where you finally take Baron. Not sure what was happening during this time, but it looks like you had around 2 opportunities to push into turrets. Additionally you could have tried for drag as it should have spawned mid-way through this gap. Also in this time gap the enemy team manages to push in 3 turrets and pick up 2 kills with no loss of their own, this is a major up swing in momentum for them, especially if the turret the minions destroyed was in that lane too. Honestly, I'm not even sure what goes wrong from here on, because the kill spread seems to indicate that you lost to a split push despite winning team fights, yet it also shows that they won by running straight down mid lane. It seems as though Kayle was able to trade your inhib for Baron once, then take it again for free.
As for issues found in both games. You took Heal as support, which is bad because the second summoner spell Heal is reduced in strength by 50% when used to frequently, this makes double Heal bot extremely bad when compared to any other summoner spell + Heal combination. You should be taking Exhaust so that you can screw over their damage dealers and completely take them out of a fight. The next major issue for both games is your lack of warding/no sightstone. Sightstone is mandatory on supports. The free wards helps you get picks, prevent dragon/baron sneaks, prevents flanks, and gives your team better map control. At least placing the wards is also necessary for this, but you placed fewer wards than most of your teammates in either game. You also didn't buy any pink wards, which can help remove enemy wards. Speaking of which, supports should also be switching to Sweeping/Oracles Lens when they get their sightstone to help remove enemy wards at key points (baron/dragon).
One last thing. Buy some Runes. They can make a huge difference early game, and sometimes even late game (surviving by 1 hp/ dealing that extra 1 damage). This isn't a huge issue in either game as Runes are more about early game advantages, but it's still a worthwhile investment.