losing hope..

My husband and I have been trying for 6 months now, tracking ovulation, taking prenatals faithfully, sex as often as every other day.. and still nothing. He has a son, I have a daughter, and we have another daughter together but we've really been wanting just one more before we hit 30. Over the last year I've been a mess. I had a baby in August 2015 and ever since I just haven't felt right. January I had no period, February it finally came, march I had two short periods, a normal period in April, and then May came. MAY WAS MISLEADING. May is when we really wanted to start trying. So we did.. two weeks late for AF and I got four different positive pregnancy tests ! Made my first appointment, and about 5 days later.. there was blood. I went to the emergency room and they tell me you weren't pregnant just late on your period. By three weeks. Since my periods have come and gone when ever they felt like it. So today I'm finally going for the beginning of tests to see what's wrong with me. They want to start with an ultrasound to make sure it isn't endometriosis.. and then on to make sure I don't have ovarian cancer. I'm scared. I've put it off for some time because idk if I can handle someone telling me that I can't have another child. Ovarian and cervical cancer runs wild on both sides of my family. Of course I'm praying for the best but I'm so afraid. I'm 25 years old.. I just want to have ONE MORE BABY. That's all.. if everyone could just pray for me today I'd really appreciate it.