I am questioning my gender and think I am ftm trans and tomorrow I'm going to a family picnic and plan on going swimming. I don't know how to explain to my family why I am wearing a shirt and shorts instead of just my bathing suit since I'm not ready to come out. My grandma knows I have a swim suit and would expect me to just wear that. I was so sneezing of someone has any suggestions so I don't have to wear just my swim suit and the only reason would wear it at all is because it hides my chest very well.
A couple that come to mind... The one you have doesn't fit/shrank/has a hole in it You just didn't feel comfortable wearing it You are a little more worried about getting a sunburn Another option, wear the shirt and shorts over the top of the swimsuit. And just say you aren't comfortable wearing just the swim wear. Or you just wanted a little more protection from the sun. It might raise some questions but just stick to your reasons.
Yeah stating that it's a comfort thing usually goes over decently well. I always wore shorts with my costume even before realising/coming out as trans and people looked at me weirdly and challenged me but I just said that I wasn't comfortable wearing a costume. What are they meant to say to that, "I don't agree, take the shorts off"? Nah. You don't owe any explanation just go and enjoy yourself the best you can.