What do I do?

Hey everyone. I kinda just need to vent and get some advice I guess. So I haven’t had a period in 3 months. Yes literally 3 whole months. December 15th was my last one. I’m very regular. I start between the 14th and the 16th of every month. I also gosh when I have my periods due to having a bleeding disorder. And because of that I’ve learned how to track it and everything. But I’ve missed it for 3 months in a row. I did go to the OB a month in a half ago and the tests came back negative. They even did a blood test. I also bled light pink and brown for a day in a half; literally the 15th of this month to the 16th. But here’s the thing. I know someone that didn’t know they were pregnant until the end of the 3rd month. I know a few people that didn’t know they were pregnant until the were 6 months pregnant 😳 and one of those people is my grandma.. 😳 and I’ve talked to a fertility doctor and she brought up a few things which some are not the case because of had those checked. One of them was a cryptic pregnancy other wise known as a stealth pregnancy.. I had talked to my grandma about what’s going on and mentioned that and she knew some people that actually had the cryptic pregnancy.. 😳 I’m actually very nervous and scared that I’m not gonna find out until I’m 6 months or even until I’m in labor.. I’ve gained a lot of weight the past 2 months, which is not normal. I monitor that very well. I feel bloated all the time and just more round in general. I’m exhausted every day. My lower back kills me every damn night. I was extremely nauseous the first month to month in a half. My fiancé and I want a baby so bad but I’m nervous that I’m gonna find out super late in the pregnancy or I’m gonna find out as I’m in labor. What do I do??