That is a tricky situation, since it is true that blankets can really get on the way. If you wanna try without blankets, maybe sure that the room is warm, otherwise, you will start feeling cold (sometimes during separation you can be a lot more sensitive to temperatures and if you physical body is not warm enough, it will bother you.)

Keep up the good work though It is good to give up after a while and try next day With such perseverance, you will OBE soon!