Is spotting before and after a period something to be concerned about when trying to conceive?

I have been trying to conceive baby # 2 for 10 months with 1 very early miscarriage in May.  I am having spotting for a few days before and after my periods (sometimes up to 4 days before) and am concerned this could be preventing pregnancy.  The spotting started after my son was born by c-section 2 years ago, but has just recently started to last longer. The spotting before my period changes from red to brown to nothing and then back again.  Near the end of my period it will sometimes go away completely for a day and then come back for another day or 2.  After it finishes, I will spot brown for several days.

I am 28 with fairly regular cycles (from 26 to 32 days long), about 10% overweight, and I chart my bbt and use ovulation prediction kits that suggest ovulation usually around cycle day 16 (earliest ever day 12 and latest day 20).  What are possible causes for the spotting and could it be preventing me from getting pregnant?