I think everyone feels this pressure to some extent (or at least anyone who cares about their degree). It's absolutely fine to have high standards for yourself. I was just trying to reassure you, and I know that I also would have been disappointed with a 41%, so I totally get your panicking. Keep aiming high!
This sounds to me like a classic combination of a few things: poor organisation, not enough research, and the 'step up' between first and second year. I'm sure you don't need me to tell you that writing an assignment the night before is hardly ideal, so being more on top of planning and doing assignments with plenty of time will undoubtedly help you.
With the essay you mentioned, that sounds like a classic example of simply not doing enough work for the assignment - not reading any academic journals, etc. I can see how newspaper sources could have a role in your subject, but they need to be more than backed up by solid academic literature. I suspect some of that came about from not being very organised, panicking a bit towards the submission deadline, and using the internet to search for sources, which will of course lead you to newspaper websites. I'm afraid that while you may have done that in first year, it *really* isn't good enough beyond that. I'm sorry if I'm sounding super-harsh, but I would expect a second year to be using proper academic literature, and maybe with contemporary examples thrown in here and there if they are relevant, for which you could use outlets like newspapers etc.
I suspect you've also had a bit of a shock in going from first to second year. The standard expected will be higher, as you've already got a year under your belt. I think you need to be a bit more organised, and work a bit 'smarter' - using things like what you learned from the careers sessions to help in assignments, allowing the time to research in academic journals, etc.
If you're referencing textbooks in your essays as a second year, then I'm not massively surprised that your grades aren't fantastic. I always tried to avoid referencing a textbook in an essay, aside from something really essential like a key definition. Anything beyond that (examples, case studies etc.) I tried to find myself, and it worked. As I said, you need to start doing some proper research for your coursework and exams - the textbook reading really is the bare minimum. A chapter a week for a course really isn't that much, and you also need to read 'smart' - look at what the textbook is citing, then go off and read those, etc.
Good luck! I hope this didn't come across as too harsh. Take this experience as a bit of a kick up the bum to do better
The fact that you can identify areas where you know you're not doing the best you can, or can try harder, is really important as that's the first step towards changing some bad habits. Keep asking for feedback etc., it will be vital, and ask about any feedback that you receive but can't understand.