i personally think that you should look at why you're creating the music in the first place. Do you want to make yourself feel better by getting these painful emotions out or do you want to convey to other people how you're feeling?
What comes out shouldn't be forced and it shouldn't be an effort to make. If it's a funk rock song about a sad emotion then so be it. If when you pick up your instrument and play a song you can feel when you're playing then you're doing everything you can and you're being a true musician.
A song about heartbreak doesn' t have to be slow and deep in the same way that a song about joy doesn't have to be upbeat. What matters is what you feel when you're writing and playing it. Write something you love about the people you love. Forget everyone else and what they might think. Music isn't meant to touch the masses. It's just a happy coincidence.