trouble with piecing/keeping end of seam straight
 

My blocks and quilts are always "skewed" outward at the corners. When I am sewing strips together, or sashing onto the quilt, no matter how much I pin, when I get towards the end of the seam, my fabric won't stay straight and I get a bit of a curve at the end of a seam. It must be the way the feed dogs work, because I have pinned the pieces straight. Hard to explain. Does anyone have a solution for this? (Assuming I was able to explain my issue.)
My machine is Janome Memory Craft 6600.

Two things off the top of my head would be to use a sharp pointed something to guide the seam thru to the end. The other would be to use a small piece of scrap to sew onto at the end of the seam, also at the beginning of the seam. These little scraps are called leaders and enders.

I have that machine also. It is not the machine really it happens with a lot of machines. If you take a stilleto, I can't spell it, lol, and when you come near the end guide the fabric with the stilleto through to the needle and it should be straight, often times we will forget right at the end to finish guiding it through. Also sometimes the feeddogs will take it wonky when not guided the rest of the way. Hope this makes sense.

And sometimes you hold too firmly to guide that last bit and it stretches, which causes it to twist like that.

I sometimes put a strip of moleskin beside my presser foot at the 1/4". Then I keep the edge of the fabric snug against that all the way through the seam. Some people use a few layers of painters tape.

Using an ender scrap piece of fabric should work--just like chain piecing it.

I hold onto my fabric with my left fingers as it goes under the foot and to the needle. this prevents the fabric from moving. the feed dogs will move it if you let them. So hang on!

I use the leaders and enders too, a flange foot, and a stiletto to keep the fabric top and bottom even to themselves and next to the flange.

My Pfaff sometimes does that as well. Leaders and enders really do help. as does using a stiletto. But when I am in a hurry and use neither, I have found that just before I get to the end of a seam if I stop with a needle down and momentarily lift the presser foot then finish the seam it is much better.

Thanks so much everyone! I'm not exactly sure how to use the stiletto, but I'm sure I will figure it out.