Going back to work, no matter the job is hard, it knocks you off your feet for a little while, plus the change in role is double the trouble! Recruitment is a hard stressful job, and takes balls, I,m in business and have done hard selling, but that is tough so you have my respect. If your boss says you are doing fine, then you are, believe me they would tell you otherwise if it weren't.
It will take time to build your contacts, learn your natural pitch, i think, give it 6 months let the job settle, you settle into working mum routine, and it will get easier.
As for stress, goes with the territory, but it will get easier once you get more confident and learn your role, you will see where you can make changes that will help, at home just say, Im tired, and its hard, and I'm scared! I get scared at least once a day, but its good to do 1 thing a day that tests you, makes it worth getting out of bed.
Sorry if i am rambling, but I understand how hard it is, but keep going, it will get easier, and if it doesn't, then make a positive change. Good Luck