Welcome to the Quilting Board!
Happens to us all! At least you didn't go any further.
Your quilting pattern is great. I did the stars about 11 years back and got confused on a couple. They have three points instead of five. I generally use the same color top and bottom. It saves a lot of problems. I pick my backing by what color I intend to quilt with
I am certainly no expert but it appears when you tried the 2 stars you bottom thread was not cooperating. Did this do it more than once? I have found on certain fabrics, that when you change direction you may be going either across the grain or with the grain that they balk doing this. I see your top fabric is denim. Try using two fabrics similar to you bottom fabric and see if it does the same thing. Try moving at different speeds. Sometimes heavier fabrics require a slower movement. Hope these are some suggestions that might help you resolve your problem.
Your stitches are nice and even and your swirly movements look nice and smooth. Keep practicig.
Thanks.. that is what I need constructive criticism! This is just practice quilt... one I had put together on a serger... But I think it is a change direction thing and my speed as I only have a speed control not a regulator yet.. my regulator is on back order.. LOL
Sorry, I only saw your first two pictures when I posted. Your third pictures looks really good. When I practice I use 2 distinctly different colors so I can see what is actually happening.
I am just guessing, is your top stitch a bit tight? You can adjust this by loosening your top tension. Be sure to use good thread on top and bottom..not surger thread on a cone...makes a big different on my machines.
Your third and 4th pictures look very good. You are doing very good controlling your movement which makes for smooth stitches. Like I said keep practicing and experiementing.