Please consult a registered therapist. Depression isn't an obvious illness and doesn't come down to "feeling sad all the time", it's much more complex than that. reply
Best bet consult a mental health professional. Depression is very common but if you don't feel like you are depressed then I'd trust your gut as you do know yourself best. Regardless even if you are not depressed seeing a therapist can help with your overall quality of life reply
It probably is depression
Take this with a grain of salt since I'm not an expert, but all depression varies and even if it's not "total breakdown depression" it's still depression. Or it could be hormones, stress, your environment, or other factors. Mostly progressing to depression or something of the sort reply
Even though you know your body the best I think you should still consult a therapist/psychiatrist to be sure. Not all depression cases are the same as the severity may change, in your case it might be high-functioning depression where the symptoms may be covered up enough to not suspect? Ofc i'm no expert but i would suggest not to brush over these...... reply