Sizing question

Just bought an authentic Nike jersey (not swingman) in small cause I keep hearing they run pretty big. I'm a solid medium in most shirts- 5'8" 145 lbs. but it was way too tight. I plan to wear them over T-shirts but don't want it to hang like a night shirt. Would large be too big? I don't have anywhere near me that sells authentic jerseys so I'm looking for advice here to not buy-return-buy-return etc.