I ordered a rash quard, I am new to surfing

It said to use my shirt size, which is Mens-Medium. I am 5 5, 125 pounds.
1.Is a Mens-Medium too big?
2.Should I have settled for a small??
If i did this wrong then i basically lost $40, shirt + shipping.
1.Is a Mens-Medium too big?
2.Should I have settled for a small??
If i did this wrong then i basically lost $40, shirt + shipping.