There is a way to minimize those "lumps" you have. We all have them from time to time, especially with star points coming together. I learned how to stop this from my friend, Eleanor Burns. She has brilliant tips about quilting and many of my quilting tips come from her. There is a link to a free download for a pattern called
Autumn-WhiteHouse on page 6 of the pattern is her step by step (with fabulous how-to photos) on how to "swirl" center seams. This is how we all do it now. Try it - it really works! Good Luck!
http://www.quiltinaday.com/freepatte...WhiteHouse.pdf