Here's what I did to get past the block you're at: Choose 4 sets of representative speakers and find a way to describe their sound. For me, it's my studio monitors, my car stereo, my HiFi stereo, and my cheap computer speakers. Listen to lots of music on each system, making mental (or notepad) notes about the general way things sound on each system. For example: In my car, things tend to sound "scooped" (less mids, more bass and highs
On my PC, music is somewhat "tinny"; And of course on my studio monitors, things are "flat".
With these adjectives in mind, it becomes easier to forgive the disparities you hear between each system. When you play your mix in the car, and it sounds bassy, you think to yourself "well, yeah, that's how it's supposed to sound."
That might help you be more relaxed when things don't sound exactly the way you want.