According to the BMI calculator I used, your BMI is 20.3 which is within the range of healthy weights, so if your weight is of a concern to you, then you probably don't need to adjust it.
Yes, you should go to the doctor's. Blood in your poop can be a sign that there's something wrong, like haemorrhoids, anal fissures, IBS or stomach ulcers. I understand it's embarrassing, but to the medical staff, it's routine to them. People who do that for a living talk about pretty much everything. They will have heard and seen things all before, and they won't judge you for it.
Hope this helps.