Ultrasound is a dynamic test. The person who does it will be able to make out better rather than pictures. It's something like a person watching a video will get a better idea than a person watching just a snapshot of the video while it's being played.
AMH between 2.5 to 3.5 will be sufficient.
Again a decision for IUI should be made considering multiple parameters like duration of married life, regularity of menstrual cycle,age,male factor etc.
Next Steps
You could consult if you wish to for a detailed evaluation and management.