Words for "a bit sad" and "a bit happy"?

Bittersweet, maybe?

M-W:

something that is bittersweet; especially : pleasure alloyed with pain

Conflicted could fit in this sense

according to Merriam-Webster's website:

Conflicted: experiencing or marked by ambivalence or a conflict especially of emotion

blitheness showing a casual and cheerful indifference considered to be callous or improper.

or air·y giving an impression of being unconcerned or not serious, typically about something taken seriously by others.

joc·und cheerful and lighthearted.

vi·va·cious (especially of a woman) attractively lively and animated.

for sadness

de·spond·en·cy a state of low spirits caused by loss of hope or courage.

disheartenment cause (someone) to lose determination or confidence.

dispiritedness having lost enthusiasm and hope; disheartened.

downheartedness discouraged; in low spirits.

mel·an·chol·y a feeling of pensive sadness, typically with no obvious cause.

gloominess feeling distressed or pessimistic.

pes·si·mism a tendency to see the worst aspect of things or believe that the worst will happen; a lack of hope or confidence in the future.

also additional word tempestuousness characterized by strong and turbulent or conflicting emotion.

hope any of this helps~