In November, Alberto "Beto" Rocasolano mad the first ascent of what could be the hardest boulder problem in Spain, La teoría del todo, at Albarracin, for which he proposed ~8C+.

According to Desnivel he needed around 40-50 sessions to do succeed, and as he already has half a dozen ~8C under his belt, the ~8C+ grade doesn't sound unreasonable.

Here is the video. Hopefully it can give you some unspiration to try just a little bit harder next time.