25yrs old.4kids in 5yrs.no period in 4yrs. spotting on pad but heavier flow in the toilet. ultrasound a good idea?

No menses: Start with the least expensive test first. I would first do a pregnancy test to see if you are pregnant, then have your thyroid level checked by a blood test to make sure that is not the reason you have not had a period. It is possible that your body was pregnant so much of the 5 years that you are not ovulating. You might be able to save some money with less intervention.

Amenorrhea: An ultrasound for not having a period is a good idea but not the first idea for me. There are so many reasons that you may not be having a period. Maybe you're a competitive gymnast or you weigh 90 pounds or you've been breastfeeding constantly. In any case your doctor will probably want to do a physical exam with pap smear and some blood work first. You may need an US later. Good luck :)

Not necessary: The periods might be heavy, except you are worried about being pregnant gain, ( you should do a pregnancy test), it is probably not necessary to do an ultrasound.