1. Have you been getting enough sleep in the past days? I did 90-hour week to finish my doctoral dissertation and much of what I did in the last days of that week was very problematic.
2. Is there some particular doubt about the project that you might have, perhaps even be suppressing in your drive to finish? It can often be wise to take time to write up these doubts. You can likely come back and review them once you are past your finish line.
3. Have the last bits of the project become unexpectedly harder and more time-consuming? This can be a sign that you need to re-evaluate your expectations about what the last steps involve.
That you've been well-motivated until recently is a very good sign. With new kinds of project, it is common for finishing off to be harder than you expect, but from the sounds of it, I think you are close to the end.