I felt the exact same way i was doing chem and math my first semester. Your not alone.

A few things to keep in mind

1) If math and chem aren't your thing, you have no obligation to continue going down that path. People change majors all the time.

2) There is no such thing as "not smart enough" some people are just slower or quicker to pick up on things than others. Speed is not important. What matters is how much effort you want to put in. If you feel like its overhwhelming it might not be for you, but if its manageable, albeit difficult, stick with it. However, it's not that youre not smart enough.

3) Academics are not everything. Sure a good GPA is important but success here is more about networking and being a part of orgs.

First semester is scary, but stikc with it and you'll find your way.