Can you have symptoms before a bfp?


So I'm not sure where I'm at in my cycle because of some thyroid issues I had last month. I completely missed a period but had a blood test ran that was neg. That was about 4 weeks ago. My cycle is typically 34 days long. If I am back on schedule AF would be due tomorrow, but I'm not sure how that I'd gonna work.

Anyways I have had a weird feeling in my lower abdomen, nausea and I just puked. I took my prenatal about a half hour before I puked, which could have caused me to puke, but this hasn't happened since I started taking them over a year ago. I have had other symptoms like light cramping but I am not convinced that they are pregnancy symptoms. I took a frer this morning with fmu and it was a very clear bfn. So my question is, can you have symptoms before a bfp? Or am I just hoping too much?