I pray well alone, but scatter behind the imam

My name is Halima Yusuf, I live in Harar and I am grandmother to nine lively ones. At fajr I kneel on the thin rug by my window, tea cooling beside me, and I can feel my heart slow, words coming soft and steady. But when I go to the small mosque and stand in a row behind the imam, everything jumps around in my head. I notice the woman in front of me's scarf, a child’s cough, whether my sleeve shows, a memory from decades ago, my focus is gone. Has anyone else felt this sharp difference? How do you live with it when your heart leaves the prayer in public rows?