Anyone frustrated with lack of progress on sleep restriction?

I'm 19 days in to sleep restriction and there have been 2 positives from it. I fall asleep within 30 minutes and I sleep in one block most nights. The problem I have been having is during my 6 hour window I always wake up 4 and a half to 5 and a half hours after I go to bed. Not a single night have I slept to the alarm.

I was expecting to have a ruff 2 weeks but be able to start increasing my sleep window but there has been no progress. Is it possible I will only be able to sleep 5 hours a night for the rest of my life?