Jungle help

So this is my first time really using the community boards and im typing on my phone, so please ignore grammatical errors. So I am a low ello player normally between gold 5 and silver 2. I feel i have a basi. understanding of pathing and and farming, however i find myself having alot of issues ganking and closing out a game. First off so i have narrowed myself down to 3 junglers, kayn, jax, and volibear. I feel i do well with these champs and have a good understanding of their potential, however i find it hard to bring in the win in alot of games. My first issue comes from ganking, i love kayn, however will no CC the early game can feel rough as is, but feels even worse when your team has every lane pushed to tower. Even worse is when the only lane you can gank has alot of mobility and is desteoying your lane as well. So first off is it acceable to just farm and invade enemy jungle? I find that no matter what choice i pick, i get blammed one way or another, which is why im looking for maybe some experienced advice or suggestions. Second problem is simply closing out the games, alot of times we need objectives but i also cant leave my team open to a 4v5. We can kill the enemy team all game but some how never have openings to take objectives. In all if someone could help i am open to all critism, and would if someone would be willing to mentor me as well i would be happy to learn. Thanks in advance for taking time to help!