بسم الله الرحمن الرحيم
This practice of yours is not good. You should go to bed early immediately after Isha salah and sleep with the intention of offering Fajr salah with jamah, you shall get up in time in-shaAllah. You should also keep on doing true taubah and istighfar.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.