" Basically, my interval training consist of 1 minute hard and 2 minutes spinning/recovering. "


That is one kind of "interval." This is training your body to do short, intense power outputs. Unfortunately, you are struggling with the longer sustained efforts.

I would start to add some longer interval sessions - ie. 3 min, 10 min, 20 min intervals. For example, yesterday I did 3 x 10 min intervals with about 4 min of rest in between. I frequently do a set of 2-3, 20 min intervals with recovery in between.