Yet another damn good reason to swim and sunbathe only at nude or clothing optional beaches.

My own opinion is completely at odds with the law on the matter of "indecent" exposure.

First off, I am emphatic on the point that there is nothing indecent about the human body, some people may let their health go they get fat, but even they have bodies that serve them decently. I say it again for emphasis, there is nothing indecent about your body.

Second off, if someone is so damned sensetive that they are offended by your naked breast, then they can simply and easily look at other things.

Whether you should cover up or not is in my opinion entirely your decision. Do you feel shy about your breasts? If so, then you can wear a bikini top, a camisole, or a tanktop or something, if not, then go topless. From my own standpoint you could go entirely nude, it would not offend or disgust me, even if there were young children present.

Unfortunately, the realities we deal with in this world... some people just cannot tollerate seeing anyone else having a good time, so they try to spread their own hatred and unhappiness around and make everyone else hate filled and unhappy. These are the people who will call the cops, so you might need to do some checking on the law before you go to any public beach or swimming pool.

It has been more that 20 years since I read the laws in my own state on "indecent exposure" so I first stronly urge you to check the laws in your state. That said, I do particularly remember that Arizona law specified that the female aurioli (nipples) needed to be covered in public, but did not say anything about male aurioli, breast development or lack of it did not even get mentioned in the law at that time.

The laws of your state are almost certainly available on the internet. Please do let us know what you find out, what you decide to do, and how it works out for you.

Sincere best wishes for good luck for you.

P.S. I found a link to a site that might offer some encouragement to you:

http://exhibitionistreview.com/news/nude-cyclist/

It depends on where you are swimming. At a big beach I wouldn't think that it would matter too much with the variety of people there. At an indoor pool where everyone is closer together then you may want to be more discreet for other people's sake, if not your own. I have worn a tee-shirt on top while swimming. Some people prefer doing that anyway to give more sun protection. You can also do that at indoor pools. Some people do that out of modesty or to cover blemishes or excess hair. I don't think you would stand out too much with an appropriate tee-shirt.
I am also developing boobs now and may end up with obvious boobs that go beyond just a well developed muscular chest. On me they are obviously not muscle - I am slim and small-framed.

I can understand your frustration with the outlandish restrictions some people must endure. I am a guy, but I have both nipples pierced, twice in each nipple, and I have been asked several times at public pools to put on a t-shirt so as not to offend anyone. And since I have a whole bunch of genital piercings, I am no longer welcome at the local naturist resort unless I remove all but one of my piercings.

My personal opinion is that anybody should be allowed to go topless, as long as they are not being lewd or lacsivious about it. After all, it's perfectly acceptable for a woman to lift her top and breastfeed a child in public, so what is so wrong about a person sitting by the pool, reading a book and working on their tan?