If your baby really doesn't like being on her tummy, leave it for now and try again another time. Bear in mind that babies develop differently, some more quickly than others. If your baby isn't rolling over by the time she is six months or seven months old, talk to your GP or health visitor.
Some men stop growing at 18, some at 21. Some men grow really quickly early on, and slowly grow taller until they have hit somewhere between 18 and 21, while others grow quickly later on and some just grow gradually. So, only time can tell you, no one else can because everyone is different.
Once boys start really growing, it doesn't take too terribly long to catch up with the other gender. Between the ages of 12 and 16, boys grow in height as much as a full foot (.3 meters). Weight gain in this same period can vary from 15 to 65 pounds (6.8 to 29.5 kilograms) [source: University of Virginia]. The first parts of the body to really gain in size are the arms, legs, hands and feet.