I agree with the answer that Jutschge has given but I would like to go a bit more into the solution of the problem you find yourself in.
You should try to play ranked games as a duo, this system tends to work better overall for player placement and skill level.
A bit more In-Depth
As you are playing normals these tend to be "unreliable" in terms of skill level, I would say I'm a good player and I mainly always have positive K/D in normal games (normally by quite a lot) but I play with a friend and most games this friend has negative K/D. Overall I am I much better player than this friend but I feel as if the system keeps giving us lower skill level opponents than we should be getting. Here is where I think the system does not work, it is hard to tell where a group of 2 should be in a normal game due to the massive skill level differences between the two.
Now moving onto the solution, playing ranked.
Now I know this will seem like ranked is clearly going to be harder and we just want to play for fun, ranked will not provide us with this but I would disagree. Ranked seems to match a lot better with who you should be playing with.
Just a word of warning the first 10 games can be hard and a little stressful as the game is finding out your skill level from these first 10 games. After the first 10 you will be placed in a league tier.
Bronze -> Silver -> Gold -> Platinum -> Diamond -> Challenger
In each of these (except challenger) have divisions from 1 to 5 (1 being the highest), you will move up and down depending if your winning or losing. (More on this here)
If you play these games with your friend you will be placed with in the same tier and the skill level the game thinks you should be at. Using your team MMR to match you with other players around that. Now the good thing is if you keep losing games it will start dropping you divisions/leagues and you should start noticing a difference in player skill of your opponents.
I would recommend trying this out and see how it does, give it a little bit of time to let the game place you a bit better then just the first 10 ranked games. Feel free to drop back and let us know how it is going.
Hope this helped, please do ask any questions about this if you have any.