Muscle takes up less room then fat. A pound is a pound is a pound. You can still be 145 lbs and have more muscle then fat. Do what makes ya happy! It doesn't matter how much you weigh!!!
I agree that a pound of muscle weighs the same as a pound of fat, but takes up less space.
If you are a healthy weight, there's no reason to worry about losing. Your height has a bearing on how much you should weigh. If you're quite tall, you can carry more weight than I can, at 5' tall.
Even at that, sometimes even being a little overweight is okay, if you're fit and healthy.
For one, 1lb of muscle weighs the same as 1lb of fat. Muscle mass takes up less space and is more compact making a person seem smaller than that of their counterpart who carries more fat. muscle can be trim looking, where fat might not be trim looking on some people. Everyone carries their weight different. If you are HEALTHY at your current weight and are perfectly happy where you are, then maintain. If YOU feel, not other people, that you may want to drop a few pounds or tone up, then by all means do what makes you happy. Sometimes, just increasing your activity level can make all the difference. Try something your curious about, kick boxing, yoga, walking around the block, etc. You might find something that helps you feel how you want to. Also, just changing your diet every couple weeks could also help you feel better. There is always going to be conflicting information that will confuse you and possibly make you feel your doing something wrong or different then you originally thought. Do what makes you happy and take bits and pieces of what you find in information. Talk with your doctor to help keep the loop open and make sure your not hurting yourself. I hope this information helps. Good Luck!
Muscle weighs more then fat if that helps.