Hello. I also came from a use calculators whenever high school.

I did not do any pre-engineering summer programs (at least you get a preview of your freshman classes) but I did struggle in Calc 1 with algebra and numerical errors at the beginning of the semester.

I went to the campus tutors and I was basically told to suck it up because my professor and departmental exams are that tough. (-_- thanks for your time)

So in your case I recommend relearning all the algebra and trig from pre calculus. By any means necessary. Don't assume you know algebra from high school or else the results wouldn't be as bad as they came out. There's khan academy but my favorites are Paul's Online Notes and a YouTube channel run by Michael van Bliezan (sp?). In general too, if homework and quizzes are choppy and painful then do not assume you'll do well on the tests (and don't rely on curves. Better to do ok not not need saving).

After you relearn the algebra and trig do as many problems as you can. On top of what you're assigned. And do not use a calculator except to check work. We are not allowed to use calculators in midterms and finals so I carried that into my homework. And take your time when doing calculations so you cultivate focus and accuracy.

Also don't feel too bad, everyone gets scalped a couple times. The academic hair grows back with effort and time. Standard ask questions and go to office hours and etc.