Every Sunday my wife and I have pizza for supper. This goes back nearly 26 years. It used to be Pizza Hut in Central Wisconsin. Now it's Costco's best frozen pepperoni cooked on a stone in our very own oven. Delicious! It's not uncommon that by the time we get to eat we are so starving that we forget the sauce just beneath the perfectly melted cheese is steaming hot. As soon as we take a bite the roof of our mouths painfully remind us we should have gone slower-let it cool.
Usually when we are desperate or needy, we move too quickly and that is when we are most likely to feel the most pain or do the most damage. Being mindful of your neediness and what does and does not help will prevent these burning, painful moments more than anything.
Think about the pizza for a moment. When we stop ourselves and let the pie cool for a few minutes it tastes the best and is highly satisfying.  Lots of food is like this. Ice cream that is too cold gives you headaches but left to sit long enough to soften becomes creamy and rich. Coffee that is too hot not only burns but can be bitter.
When you are just remarried your motives are right to want to make this union better and without the mistakes of the previous marriage. This desire unchecked can lead to pushing too hard for compliance from your children, stepchildren or spouse. Blending families takes longer and ironically pushing too hard, too fast actually will slow the blending process down-even stop it.
While your motives might be right your awareness of the intensity of your neediness might not be as great as you think. Have you been feeling frustrated frequently? Are your feelings hurt too easily? Do you have anxiousness that rarely goes away?  Answering yes to questions like these might indicate a higher level of defensiveness, neediness, unresolved losses, etc.
Take a week or two and make a running log of these frustrating or hurting moments. Then prayerfully read through them looking for themes and clues as to what are the real driving forces. It might not be just you. Your child might be resisting for her own unresolved reasons. While you thought you connected great with your stepchild before the wedding, afterwards it has been different with him-because life became more complicated. Journal these clues and observe yourself and your family for a few more weeks. See if you can identify the still hot issues in your heart and mind (or the kids and spouse).
If you can raise your awareness of these hotpoints, slow down in your attempts to blend too perfectly, too soon, you might be able to enjoy your family more often. That already sounds more peaceful and satisfying.