Why am i having trouble reaching a meditative/blissful state?

i begun meditation 4 months ago, and i begun meditating 10 minutes everyday and slowly overtime i added time to it and now i can do it for 40 minutes. after a month, i begun to notice that i could get into a meditative state much faster than it would take me if I had done it once a week for an hour or hour in a half like i could feel more relaxed and more happier after the meditation. While meditating i sit in a posture with my back straight and cross legged and hands in lap I also listen to mantra music while i meditate which does help me concentrate, i used i repeat the mantra while i meditated for 20 minutes or so and i slowly reached the meditative or blissful state .I had noticed that i begun having some problems while i was meditating and i kept putting my head down because i had felt as if someone was going grab me by the neck and this i think was due to my anxiety and this was why i wanted to meditate so i could help fix this problem and this whole neck grabbing thoughts started after 2 months and now i haven't been able to get into a meditative state as i used to before.i also stopped repeating the mantra and it only made things worse because i had thoughts arising in my head. Now mostly every time i meditate i feel a little relaxed and i was wondering if this is a part of meditation, to feel relaxed afterwards even though ihaven'tt reached that blissful or meditative state and why are these thoughtsinterruptingg me after 4 months of meditation p.s i had begun repeating mantra a few days ago and i meditate 2 a day 30-40 minutes for each session.