Feeling Overwhelmed in College: Need Advice

I’m not sure if this is related to adhd or if anyone can relate to this or not… but I’m going into my sophomore year of college and I’m a STEM mayor so I know I have to put in a ton of time in studying and understanding the material, but recently I’ve been stressing about whether or not I’m spending too much time trying to understand the material. Basically whether I’m just a slow learner or if I’m just not getting it. I don’t want to put my all in and it still not be good enough but idek when I’d be able to tell if I’m not cut out for this degree plan. I still think I can do it but my dad tells me to think about other options just in case. Does anyone relate or have any advice for me? I desperately need some.