Her career = getting loads of freebies and exotic trips. The FOMO was so evident right after she had the baby and Anna was taking these spon trips to places and fancy spa hotels but Lily couldn't go.
I think she's also following other people (some mentioned on this thread that I don't know) who seem to actually enjoy motherhood and she's thinking if she tells herself that she's loving every minute of it, she actually might. Also I think she's probably watching Fleur's vlogs now who's clearly grown into her role as a mother and sharing her lockdown with River and Mike, having fun, cooking together and I guess Lily resents not having that kind of life. I'm sure Fleur's life also has its downsides we don't see and there's struggles but obviously they're enjoying time together as a family. I guess Lily's annoyed that Rich actually works properly at least some days of the week and that she doesn't have a mansion with gardens to hang out in and that her kid likes plastic toys.
On the other hand she then complains when Rich expresses that he wants a family that bikes together or does any sort of activity outside of the house.
I honestly think she's struggling now more than ever is because she's never been creative, but now it is also becoming more evident that she's got no real interests, no hobbies, no skills. NOTHING to share with Rich and Grey, nothing that can be used for content.