I need help with measurements for a 2t romper please (w Sewing Machines Parts and Sales in Los Angeles

http://imgur.com/chTuJP7

I’m making a romper for my bosses grandkids and am having a hard time with measurements. I don’t really get patterns because I mess up in them. Here’s my issue. I can’t seem to find a measurement from chest to groin. I was only able to find a back measurement and a rise. So I’m figuring my back measurement can also work for my front measurement of the front top portion of the romper. I also found a rise measurement of 18.5, so I divided my rise by 2, took an inch in the front and add an inch in the back For the shorts portion of the romper. So as a total measurement for the front I have 16.5 (chest to groin) and 10.5 in the back. Is my front measurement too small or short for a 2t? If I’m confusing or if you have questions ask away. I just want to get this right