Nausea, Heartburn, Constipation, Headache. Negative Pregnancy Test. Could Bleeding Cause Low HCG Levels?

Hi, tryin to conceive..32 yrs old,2 children. My cycle is every 28 29 30 days and last 4 days (5 depending on how u count). Irregular but i have a norm . Have been tracking for about 3yrs now. Every blue moon ill come on the 31st day but very rare. Feb 7th was last normal period.. In Mar., on the 9th, the 31st day, my period was a day late (i consider anything past the 30th day late for me) but it was light and the most blood i had was 1 day, the day AFTER i started, barely nothing the day of starting, the remaining days were light bleeding and spotting, i ended Mar 13th, the 14th test neg...Mar 21-28th, i was nauseated, Mar 21 to Apr 10th breast were sore very tired...I started period Apr. 8th, on time, the 30th day. It was light again, on and off bleeding for about 2 days but not heavy like it usually is, barely nothin the day of starting..I felt fine in April until i became nauseated again April 29,30, and May 3rd..So here in May i was 2 days late, i started May 10th...barely nothing again the day of starting, on and off bleeding the next day with clots, by the 2nd day i was cramping bad with barely any blood, i began spotting and it stayed that way the remainder of the days, ended May 14th test neg..Also the 14th, felt nauseous with heartburn and constipation ....the 15th still constipated very gassy and bloated. The 16th still constipated and gassy, an on and off headache along with minor heartburn, and when i go down stairs, i notice my breast feel sore as im bouncin down. With my daughter i knew i was pregnant as soon as my period stopped short on the 3rd day and never came back, i kept taking test saying negative, but i knew, but didnt confirm until i missed my next period the following month...My aunt didnt find out she was pregnant until she was 5 months by ultrasound , and she was on number 3, she kept having periods and negative test, she only went to doctors because her stomach was getting bigger and she felt movement. My questions are: considering i was a day late in Mar and then 2 days late in May, is it possible i could be pregnant and since im bleeding every month could the bleeding be causing low hcg levels preventing a positive test? I feel like i am and am worried that im months along and its not showing up because i havent missed a period. I feel weird sensations in my abdomen but dont know if im tripping or if its gas.. Thanks