It's very common to see players who don't know how to play differently when they're behind or losing in lane. You simply have to respect the difference in items or level that your opponent has on you. If you come into lane and you're two levels down or your enemy laner has a significant item on you, then you have to play very safe and probably won't be able to get back into the game without a roaming kill or a gank from a teammate. However, don't make the mistake of doing nothing but roaming and letting your opponent free farm. This is something I see all the time with people. They will be losing lane and try to get fed off kills, but they already fed their opponent and he's getting easy CS on top of it, and it's just not going to balance out most of the time.
Some champions are better at 2v1 lanes than others, and honestly at low level like that it's not a good idea to solo top or jungle unless the person in each respective role knows what to do when there's a 2v1 lane. The top player should be prepared for a 2v1 match-up and the jungler simply needs to gank because a 2v1 lane will naturally push to the tower. Your job is to survive until that happens with enough hp for your jungler to make a play on the lane. I would recommend picking up some champions that are a little more efficient at a 2v1 top if you are going to have a jungler at low levels. Some examples would be Rumble, Gangplank, Wukong, Cho'Gath, Vladimir, and Kayle.