I can comment on this one i am a mom. You probably want to remember what your mom and OBGYN told you about the delivery......it puts alot of strain on a womans body and take up to 6 months to a year for your body to return to normal because the baby took alot of your vitamins, etc. from your body as he/she grew inside of you. For 100% sure stay away from caffeine my friend....that means not only coffee but iced tea, colored sodas, chocolate, etc. because you are just irritating it. Your pulse rate is within normal limits for the standards set but remember you just had a baby and i am sure you still remember how hard and long you went thru labor. I would talk to my doc about it but not only did you have an infection going on, you now have a new baby to care for and alot more responsibility at home and stress may also be an issue here. When we are active our heart def. goes up as it should.....sort of like exercising the heart. Talk to a doc....write down your worries and congrats on your new baby....i am sure as time goes on if the doc says you are fine you'll adjust like we all had too.......
I just started getting sinus tach last year and started a beta blocker. I really did help me for the last year, but now it doesn't seem to be working as well. I was really hesitant to start taking meds for this, but I couldn't tolerate the constant nagging heart rate. It was driving me crazy. Good luck.
The HR you give are "borderline" Tachycardia and if you do not have any other symptoms then it seems you could just "live with it". Or, perhaps a low dose beta blocker can slow down you HR with minimal side effects.
My comments are limited to my experience with a high HR that is controlled with beta blocker medication. I'm a guy, so I have no experience with childbirth, but it sound reasonable that if you had high blood loss that you HR might be higher until that is corrected. I'm just relating to what you posted, I do have specific knowledge or experience, other than I had year ago a critically low hemoglobin count (same as blood loss) and I had to have blood transfusions to get back on the path to normal counts. I do not recall having any heart symptoms... albeit the low count on my part developed over a long (unknown) period of time, so my system had a chance to adjust to the loss of red blood cells.
Bottom line, get your doctor's recommendations on how to lower you HR.