I was going to write a long reply, but marckee’s basically nailed the best route. By omitting the first sits you’re not lying, just obscuring slightly so the worst that can happen is someone will sift you out on the basis that it looks like you’re hiding something. Far more likely they won’t notice.
As someone who’s sifted a lot of CVs, you need to keep in mind that for many jobs, and certainly those with large numbers of similar applicants, your CV will get about 30 seconds of attention before being either thrown on a “possibles” pile or an “outright reject” pile. Your degree will probably be the first thing they look at, then probably your other education grades. Nobody will be perusing the dates until they sift the possibles again, if they bother to. At that point the rest of your CV will be getting more attention.
You might get asked about it at an interview. If you are, tell the truth. What you did shows character and perseverance, not failure, so you should present it that way when asked to account for yourself. Any good boss will rate that, any bad one can go fuck themselves.
Good luck, and try not to worry about it too much.