Yes def. use stitch markers. I gave up on my 1st lace project thining it was somthing I just couldn't do, but when I used stitch markers, I discovered I can do it. When I get stuck, I can just look back at the repeats and count the sts, and can tell where I goofed. Plus, so that I don't lose my place, I often will write the sts out on another page for a row, and then use a pencil to mark it out as I so them, and that helps me alot. Often, if you just get familiar with the pattern and learn the flow of it, you will get good at knowing, what comes next, and what goes where. That way, you will catch a mistake much sooner.
The sts work out, so I am assuming you are doing something wrong. I would do what SuzeeQ said and go through and try to read your sts and see where it is coming up wrong.