I remember this stage when my kids were little. What helped was when someone told me to change my attitude from being a teenager, when Shabbos was relaxing, to thinking of myself as the Rav of a big Shul, where I am “on-duty” all of Shabbos.
If I stopped expecting to be able to sleep, read, and relax over Shabbos, and I expected this to be my time to actively work, then I was much happier.
Many of the other practical suggestions in this thread will help you as well – Hatzlacha!