Yes, even last year we found O Cebreiro & Triacastilla were the 2 most difficult places (in May) to get a bed.
My advice would be get into both early. Which is a bit harder with O Cebreiro because of the climb, but it is way worth the effort to get there early, not only for a bed but time to enjoy it.
Triacastilla, well that's another story, get there ealry to get a bed, There's supposedly more bed's there than O Cebreiro but somehow the crowd multiplies on the way down the hill.
There are a couple of option just before Triacastilla you might check every opportunity along the way.
However, don't be fearful, even the difficult spots seem to work out OK. In Triacastilla we ended up getting a Taxi to a bed in a rural area, taxi driver came and picked us up the next morning and dropped us off at the same spot in Triacastilla, 7 euros each way. It will sort itself out somehow.
Buen Camino
Col