Finally, I was able to solve the problem.
Since the size of the sd card was correctly set to 1 GB, according to my settings, I just copied the sdcard.img file and renamed it to userdata.img and userdata-qemu.img (in the avd folder):

After rebooting the emulator, the phone's memory size increased! I donβt know why userdata-qemu.img is much larger and now I have only 1.89GB.

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