Could I have conceived or too early?

I have 2 boys ages 2 and 5, in September I lost my daughter at 18 weeks. She had been my only child I had tracked my fertility with and I felt as if I knew the moment I had conceived her. I am TTC again and I have that gut feeling I have conceived again. But I am still in my fertile window according to tracking my period. I have had a headache every day the past 4 days, I feel like little bubbles popping in my pelvic area and I am feeling little twinges and cramping in my uterus, I feel bloated and I have been feeling so hungry but feel full quick, urinating a little more frequent and I have been feeling nauseous the past few days, but my boobs aren't sore. I don't know if I am just getting my hopes up or if this could be it. Could I just be ovulating or have I possibly already ovulated? My period in March was very light and lasted about 3 ½ days. But I have taken a hpt and it was negative so I know it was my period, not implantation. Has anyone else had this feeling and what was the result of it?