After breeding Bunny at least once, "Finish mating" to continue towards the Forest.
If your Determination runs out too fast, try playing trough from the start. The "Reach Bunny" button is convenient but wastes any speedup you gained since the last time you reached that point manually. If the "Idle" stat in the recap exceeds 3 it's probably time to refresh your route.
Please let me know if this solves your issue. I think those are the most likely points of confusion, but if your issue is something else I want to know.