help I hope I will have a 4 baby!

Ok so I took a test march 1 and it didn't show positive right away. I don't start period till the 5 I took several test now they show up quick. I went to the doc and did ultra sound and she said the sac wasn't round enough! And she said for how far along I should be there's nothing but that I might have ovulated late. I have really no symptoms but wanting to sleep on my left side and craving stuff and not wanting to eat things. Do u think I'll miss carry. I have three kids all boys 7, 2, 5 months I did have a miscarriage before my second but I bleed. But nothing this time I actually feel really good help!