I feel so alone in my relationship.
Why are you so alone? What about your bf?
It's, well... I feel like there is no affection between us.
You should find others to spend time with. If your bf isn't there for you, you should find others.
It's my parents fault. They don't let me hang out after school.
Have you tried joining after school activities or clubs? You can try to hang out with your friends there and you parents might approve. You don't need to feel alone because it can be really harmful to your psyche.