Yes, I go to the extreme end and then start again in the middle.
I start and end every line with small stitches then gradually increase.
I also bury my thread in the middle. Leave enough thread when you start
a new line so you can thread a needle and bury it just at its source then
make a few stitches through the batting, bring the needle up and cut the
thread. I'll try to make a diagram and post in a few.
I always use same thread top and bobbin to avoid the kind of problem
you're having. I read it's very difficult to control when using two different
colors. I use some neutral color and I'm done. :D