How to tell my partner I need more affection?

I am so lonely in my own home even though I'm with my partner 90% of the time. We never kiss, hug or cuddle, and only have sex twice a month and don't cuddle afterwards. We don't really flirt, we're just kind of "flat".. I sleep in a separate bedroom with our 5 month old baby because he won't sleep in a crib and I have to cosleep. How do I let my partner know that I need a little love, reassurance and affection?