Well first off all I would say that it is super important that you take some "me"-time for yourself every day. As as new mom you have a million things to do, and it is hard to see yourself taking even a minute or two from your non-stop schedule of diaper changes, feedings, soothing and much more. However, it is SO important that you arrange an hour or even 15-20 minutes a day where you do something that makes YOU relax. As a fitness profesional I will of course recommend exercise as a great option, but it could be anything from reading a book, to using an acupressure mat (I used the one from TheraMat - www.TheraMat.com). What is important is that it makes YOU relax and gives you a break from your hectic schedule. And trust me, your baby will be just fine without you for an hour, and you will be a much better mom giving yourself this short break every day!
Also try to arrange to have some healthy snacks available at home at all times. It is hart to take yourself time to prepare a good healthy meal for yourself (at least it was for me :) !) and a lot of times you end-up snacking throughout the day, so being prepared with some great healthy option will make it easier to stay healthy. Examples of snacks could be peeled mini-carrots, grapes, or low fat yogurt (without sugar, instead use fresh berres or fruit with it).
Third I will say, stop stressing about being that perfect mom you read about or that you think your friends are. It is impossible to stay up to date on everything, and do everything that they say is the right way to do things.You know YOUR baby, and as long as you try your best to care for you child, you WILL BE the perfect mom for your child!