I think you are probs right in thinking you have too many trophies for your level. The same happens to me and has done so for months. At the mo I am lvl103 and once I pass 7K trophies I become a plaything for the top guys until I drop to about 6.7K.
I don't know the true mechanics of the game but think trophy count must determine which map you appear on, look for the point when you start getting thrashed then aim to stay just under that. I know it doesn't help you much but that's what I do.
When I look at the games top 10 peeps I think hey I've donated trophies to most of them lol.