dizziness after eating

hello!
well , every day I wake up fine and happy, then i drink water and do some stuff, then i have breakfast, ten minutes later I need to lay down because I feel so dizzy, my eye movement gets very slow and my head gets confused, feel a little unbalanced , drunk feeling,and sometimes i pass out. and I never know how long this drunk feeling will last. sometimes i feel well one hour later, sometimes it can last the whole morning and in the worse scenario it lasts the whole day. When it lasts one hour then i´m happy again, but, if i eat a midmorning snack i get dizzy again. mosts of the times i´m fine by midday after lunch. I was diagnosed with vasovagal syncope after a tilt test, could this be related to it? i´m skinny, female, and my blood pressure rarely changes it´s most of the time 90/70, which my doctor said its not that bad since i´m skinny, he said something like maybe there isn´t enough blood in my system or something like that and i´m not getting  enough blood to my brain, but i dont really understand that. like is there any way that the blood volume or whatever it is, can be meassured? or doctors just know that? My bp doesnt goes that low after i eat, it maybe gets like 87/67 for example. what can this be? i´m confused and worried that i´m not getting blood to my brain, i forget everything, feel confused most of the time, sometimes i´m driving and don´t remember where i was going and need to stop a little,i´m happy with my liffe, i´m not depressed, not stressed out,  i´ve tried all kind of different foods but i just keep on getting dizzy, it seems to happen most with fruit, oily food,sugary stuff, but it actually happens with everything. can somebody help me and give some ideas?  a got hundreds of tests and everything comes back normal, including glucose test and brain mri. Thenk you so much!! aprecciate your answer!

[xizzor]

You have mentioned your bloodpressures,
but what is your heartrate like when you feel fine...
compared with when you're feeling like a zombie?

If it is significantly lower then I guess the drop in bloodpressure could be caused
by a drop in HR, which could be caused by a hypersensitive organ in your body that gets activated by eating - and as the day progresses that particular organ becomes less sensitive.

This is just a quick theory about something unusual,
I'm no expert by far but I guess the question about the heartrate is a good one.

If a drop in HR causes a drop in BP, then the drop in HR can definately be caused by mental factors as well.
Sometimes all it takes to start experiencing symptoms of dizziness (or whatever symptom it may be)
is to think "here i go again".