Gearing is important, your own level of fitness and said gearing are most likely what is holding you back the most. What are you using on the Tricross? There isn't anything special about riding fixed for road training. As you may know, in the past riders would often just swap out their rear wheel and ride the same bike fixed for the winter.

Fixed gear training is/was usually done with other fixed gear riders using similar gear ratios OR done solo. Trying to go on group rides with a bunch of geared riders probably won't work well if they're even a little bit competitive or doing any sort of structured training.