since got pregnant have had increased heart rate after eating!

I am 20 weeks pregnant now, and for about 2 1/2 months now I've noticed that my heart rate increases after eating about 95% of the time. It takes about a half an hour before it begins to do that (never longer), and lasts anywhere between 1/2 an hr to an hour and 1/2. Does not seem to matter what I eat or how relaxed I am. This has been a high risk pregnancy, I had a blood clot in my brain that permanently damaged my right eye, I have had every possible test, procedure and lab work done with no findings at all as to why this happened. I have no health problems otherwise, I do have palpitations that I've had for 5 years now with also no findings on that. I am on no meds as of now. This problem is very uncomfortable and I would love some answers, I did ask my Dr. and she just kinda went past it but I will pursue it some more next visit. Thank you for any info on the matter.