I [15F] feel like I overthink things with my boyfriend [17M]

My boyfriend and I have been together for about 7 months and things are mostly really good. But sometimes I overthink small things, like if he replies later than usual or seems a bit quieter.

My mind starts wondering if something is wrong or if I did something, even though he hasn’t actually done anything to make me think that.

I don’t want to create problems in my head or let overthinking affect our relationship.

How can I stop overthinking things like this in my relationship without making it a bigger issue?