I can purchase a binder now but i can't tell my parents what exactly it does-so if my mom washes it will she know that it compresses? i am thinking of buying a full length one so it looks like the regular vest that i wear.

If you get a full length one I don't think she would be able to tell its for compression. If your getting it from underworks its got a mesh-like feel to it so its not gonna feel like a regular tank top but they are the best in my opinion. Also the ones from underworks it has to be washed in cold water and with no softener. I just wash mine in the sink because it helps it last longer, so you may not even need to have her wash it or even really know you have it if you wash it in the sink. Congratulations though, its a liberating feeling to put on your first binder and look down and see nothing there

Some of the long binders have stomach compression, might not be something you want (some people do like this). Something to think about when buying.

--Jay

Like Jay said - I used to wear the longer binders, but I wound up having stomach issues so I switched.

They do last longer if you hand wash them, so maybe that is best?

Don't have her wash it, if it goes through the dryer it won't last long.

I think the purpose of binders are pretty obvious.  I would suggest hand washing and keep it out of the laundry.

So I would tell her not to wash it or just say that it is not that tight as it seems-hardly think she would care once i say any explanation.
The full length one is my only option as i don't wear a br., so a mid size would raise questions.
but i looked up online-underworks and mansculpture have no size-chart for height-i'm 4'9" and there is mention of height on t-kingdom and some e-bay sellers- Otherwise an M size is right for me.How do i figure out the right size for my height?

If your that short in the torso then you can just fold up the end a bit like I do. I don't think height is a factor, at least with the 997 from underworks.