Most people know that being both over weight and under weight are not good for you, but health is about far more than just body weight. Things such as your family medical history, your genetic predispositions, how much you drink or smoke, what type of food you eat and how much exercise you get all have a major impact on health. There really is no ideal weight therefore that you should be seeking on purely health grounds.
Using your weight as a measure of health therefore is not particularly useful. Obviously there are levels that will definitely be too high or too low, but within these limits, there is a huge range of healthy weights that people will fall into. Much of the worries that people feel regarding their weight are more to do with media images and glamorous advertisements than on what is considered healthy. We are surrounded by images and conceptions of beauty that distort our idea of what a healthy body should look like.
Many media images actually show people who are under weight, sometimes considerable underweight, and do not represent a healthy standard or good example to measure us against.
If you are genuinely concerned about health, then weight loss should not be the ultimate goal of all fitness efforts. You should try to cut down on cigarette and alcohol consumption, eat healthy food, get a reasonable amount of exercise, and generally take care of yourself. You do not need scientific advice and a professionally designed eating and exercise schedule. More likely what you need is common sense simple changes like snacking on fruits sometimes, walking to work, and visiting your doctor when recommended.
Doctor check ups are recommended at varying intervals depending on your age and health circumstances but it is wise to keep up to date with these checkups and not to fall into the trap of constantly procrastinating. If the cost of doctor visits is a serious issue that causes you to skip visits, then maybe you should consider a health insurance plan that will cover such checkups and just charge you an affordable monthly amount.