RBC below normal

I'm a 36yo male. I've been fighting IBS-C for 5 years and have it semi under control with fiber and diet. I've been very run down lately which I attribute to IBS and not working out as much. I got blood work done and had slightly below normal Hemogobin (13.8) and hematocrit (39.7). All other CBC, ferritin, thyroid etc results were normal. For reference, one year ago these values were Hemogobin (15.8) and hematocrit (44.5).  I've had a colon polyp removed this year and do have some minor bleeding from hemmorhoids. My doctor (actually the nurse practioner) said there was nothing abnormal about these results. This might be true, but what type of possible symptoms should I be looking for in the future? Should I ask for any other tests or get re-tested in the near future? Thanks