It might be a good idea to pick a jungler with strong early ganks. Udyr's ganks are rather sub-par (compared to many champions) and Diana can't reliably gank pre-6.
From what I remember of my (30) Silver games, most games tended to snowball heavily for one side or the other rather early. Picking a strong early ganker can let you snowball your lanes, demoralizing the enemy and potentially preventing your allies from feeding. If you get your allies far enough ahead, you should be able to win relatively easily.
If you want to stick to Diana, you might want to rush Zhonya's Hourglass after Runeglaive in many situations. This item allows you to initiate fights for your team and stall long enough for them to follow-up.
Taking a quick look at your match history, I can see that you rarely upgrade your trinket. At lower levels of play, I would suggest purchasing Greater Stealth Totem in most situations (Sweeper isn't as important since enemies don't frequently ward at that level). You can easily have three wards down at all time with the upgraded trinket, which provides a lot of vision for your team to arrange picks or avoid getting caught out.
I would pretty much always recommend upgrading it around level 9 or 10. 250G is pretty much nothing unless it prevents you from immediately completing a major item and it offers massive gold value. I can often get around 20-30 wards in a game with nothing but the trinket.
Learning to ward properly is one of the easiest things you can do to improve your gameplay. It's crucial and quite easy.
