Scared need advice

So I've had my period since I was 14 actually came on my birthday 😔 but since my first period I've had horrible cramps shaking throwing up once even in the ER the first day is the worst but I'm in pain all 5 days. I married in October 2013 got pregnant in June 2014 miscarried in the 10th week 4 months later pregnant again and miscarried on my 6th week on Christmas Day 😔 since then my period has been crazy when it comes its even more painful then before the blood clots are huge sometimes and so painful in 2015 I had 4 real periods one for almost a month told my doctor didn't do anything said it was normal now in 2016 I just finished my second period this year since April in April it was only a little cramping this period I had to stay in bed for 3 days with sharp pains. My doctor is just saying it is normal and I'm beginning to get scared I'll never be able to conceive because of my very irregular periods. we have been trying to conceive since beginning of this year. Since married I have not used any birth control except condoms. I just turned 24. I am also scared it could be something else.