Been having pregnancy like symptoms. Took femara (letrozole) about 3 weeks ago, had blood test for progesterone day 21 level, came back. 4 and had ultrasound done which said I ovulated. Could I be pregnant, be having ectopic pregnancy, or miscarrying?

See your physician. Have a bhcg quantatative done, not bhcg qualatative. It would be good to see what your bhcg number is to determine if you are pregnant. Most home preganancy tests are qualatative which tells you if you are pregnant or not. A quantatative test will provide a "number" to indicate "how much" of a product is produced.
Ulikely pregnancy. The Progesterone is too low to maintain a pregnancy. Ultrasound should show an ectopic pregnancy. If fertilization did occur, probably did not implant and maintain in part due to inadequate progesterone.