Why do we make thing's harder then we should?

I'm half way thru my 2nd week of school and I am starting to feel very overwhelmed! Last night was a really hard night! Not understanding anything in my Human A&P class I found out that I had 3 homework assignments and 2 quizzes to do before 10:30 last night! I had 4 hours to do them all! I did the quizzes first and didn't do so well I'm sure and the homework wasn't any better! I have never done well with understanding from just reading and not having anything explained to where I can understand! There is a lot of reading and the first couple of chapters are thing's I don't understand and have never really understood! So I'm sure that taking tests are going to be harder! Last night and this morning I was ready to drop the class! After class I felt like I needed to give it more time! Although I have met someone in class that said she would help me if I needed it and I will probably take her up on that, it still is very overwhelming. I try to keep telling myself that all I can do is my best and if I fail then at lest I did my best and tried to figure it out! I'm really liking my math class (who would of known) weird cause I've NEVER liked math at all! I'm sure once we get farther into it it's going to get more challenging but I have someone to help me and I have a really good teacher! I don't so much about my medical terminology class cause I've only gone once. It's more memorizing and learning to say the medical terms right! That's where I have a hard time cause I've never been good at pronunciation but it goes back to I have to try and do my best cause that's all I can do!
 Today in Human A&P lab we dissected a rat today. That was kinda gross which make me think what am I doing going into a field that I have to be in surgery! I gagged a couple of times. The smell was horrible so I was trying to just breath thru my mouth but that didn't work the whole time! Although it was interesting to see the insides it was hard to touch it and not smell it! While I was holding it while the other girl was cutting I think I broke it's leg (not that it really matter cause it's dead but I thought I'd throw it in), one of the girls heard it and freaked out from the sound. I kinda laughed that I did it. I really wish that I would learn to stop freaking out and just know that all I can do is my best so I can go full force at things and not worry about a week, month, 6 months or even a year from now! I need to work on the here and now!