Let me just preface by saying that I'm very new to blender and I'm sorry if I don't use the correct terminology. I hope that I'm making sense with how I'm describing my issue.
So I have no idea why but whenever I use the subdivision surface modifier it cuts up parts of my object? I have no idea why and would like to know how I can fix this since I really need to use it for round parts of the object that need it. I did already use the edge split modifier and that helped a lot but now I would like to use the subdivision surface modifier. I already have tried doing smoothing on it but didn't give me the kind of help that the subdivision surface does for it. I did also try to separate the object and that did work, however, I need my object to be only one (sorry, I don't know how to explain this?) and splitting it up caused me a lot of trouble to fix it. Or, if there is another way to smooth my round top and bottom (besides bevel) then I would be so appreciative.
Here are some photos (Top is when the modifier is applied, bottom is in edit mode and the top sides are what I'm trying to smooth out):