Having played hon and dota, you probably have the basic mechanics of creep killing, denying (which LOL doesn't have), when to push and so on. The rest of the game is really learning each and every champion, and in your case, making comparisons with similar champions in hon and dota. A lot of champions are similar in all 3 games, however the animation of the spell and damage might be different.
The other thing, you might not be use to in LOL are summoner spells and a lot more mana regen/spell usage compare to the other 2 games. Granted from what you said, you are doing decent and other players are feeding is pretty typical especially when it comes with lower levels since there are a lot of newbies learning the game fresh or/and smurfs (lv 30 people playing on low level accounts).
Just keep playing if you enjoy the game

bare the pain of newbies, cause there are more when you hit max level xD