Irregular or not ?

Ok so I have a huge problem an it seems like my doctor's can't find anything. I have a irregular period which is normal as long as I have it three times in a year I should be fine but from the first time it's gotten less and less. Now I get my cycle once sometimes twice in one year. In addition to they when I don't have my cycle for a while one day or week out of the month I am in A LOT of pain as if pins an needles are sticking into my vagina. I get nauseous and then have to sit down an try to rest but there will be no bleeding!! I tried explaining this to my doctor and they sent me to the hospital to get and ultra sound and they didn't find anything, can someone help me understand this please 😭