The teams you are matched against in raids has nothing to do with the team’s attack power. In fact, attack power is very misleading when it comes to judging a team’s strength.
You are matched based on the number of CUPS you’re holding. Your defense team holds cups while you’re off line based on how they fair against attackers. However, an attack team and a defense team are comprised of very different heroes (the best heroes are used for both, but we don’t all have those).
It sounds like your defense team can hold higher cups than your attack team can deal with. Try switching your defense up, so when you wake up each day, you’re at 1800 cups or so. Fights will be easier, your chests will get filed. As your roster expands, you’ll be able to handle harder teams on offense, and your defense can be adjusted to hold a higher cup count.
For example, I can hold about 2600 cups with my best defense team, but filling my chest each day at that level puts me over 2700/2800, and fights become very challenging (and repetitive). So, I use a weaker Defense team and drop to 2400 each morning. It works well.