Well, I changed the needle and I still got the same undesirable results. So, the next thing I tried was to adjust the tension. It was on 4 so I tried about 3.5 and the problem got worse.
Then I tried it about 4.5 and my stitches came out a lot better.
Also, I changed the kind of thread I was using. I think that made a big difference too. Now it looks great!
Thanks all for your help and suggestions. You're the best! :thumbup: