New job not the right fit, should I move on?

I left a job after 3 months for what seemed like a good opportunity that I would regret not taking. Now I'm into my fourth month at this new job and i am miserable. I don't enjoy the work, the schedule has hours that mean I'm not able to be with my family as much, the training was minimal at best. I have stayed because i thought it was just new job anxiety and that I would find my feet but nothing has changed yet. The workload is high, and i feel like i never complete enough, nor give enough attention to each task. When I ask my colleagues they say it's just the way it is. I am not sleeping well,and I struggle to get rid of any worries when I'm at home just thinking of having to go back in to work the next day. Is it acceptable to start planning to leave a job after such a short time or am I better to stick it out and work on trying to get healthier mentally and then look for new opportunities? I have started attending a mindfulness course to see if I can learn to stress less, and trying to plan things outside of work to break my overthinking. Does anyone have experience of something similar and if so how did it work out? Thanks for taking the time to read.

I have had similar jobs. Honest advice, is to stick with it until you find something better. Keep in mind though, if you leave every job after 3-4 months, interviewers will start to lose interest in hiring you because they'll just have to do interviews again in 3-4 months when you quit.

Thank you for your advice, I am sticking at it as long as I can handle it. Really appreciate your help.

Thanks for your advice. I just got a new schedule with extra hours added to cover staff who have left this month so it feels like nothing will improve no matter what I do. I appreciate your help.