S.H.
In my experience it's pretty normal. I also breast fed exclusively with my first but still got my period back when she was 3 months! Like you, it would be barely there one month, heavier the next, and then skip a month once in a while. My second daughter is 5 months and I've spotted a few times but nothing consistent. Hope that's not TMI - just wanted you to know it's not uncommon. One more thing - I took a few pregnancy tests during the 14 months I breast fed my first daughter - especially if I was inconsistent from month to month. With both my girls my period/spotting started when they started sleeping through the night. If you still feel unsure don't hesitate to ask your health care provider:)
Blessings:)