More blood work

2 weeks ago I went get blood work done to see if I ovulated the week before but when I got my results in my levels were low... so my doctor told me make an appointment when my period starts and on day 3 she wants more blood work well tomorrow will be day 3.. any ideas what she would be testing for? And my doctor wants me to get an ultrasound done on CD 13 because that’s when I’m supposed to ovulate but with my luck my ovulation day lands on the weekend so I’ll be going back in 2 weeks for an ultrasound.. any idea what she would be doing that for? Sorry for the long post and questions I’m just nervous for what I may find out later on if I get bad new back 😕