hi,welcome to HCM,
I read your problem,you r feeling pragnancy like symptomes since middle of the march.you have period for two days in march+april. your HPTs r negatives. I think nothing to worry for pragnancy because some time due
stress,psycologicaly u feel like
pregnancy it is called psuedosyaesis.but
sonography by yr GP shows endometrial thickning.so u have to take expert opnion of sonologist [repeat sonography by radiologyst]. and if report suggest something related then take gyneac consultation