It's totally normal for it to take months, if not up to a year for your period to return, especially if you're breastfeeding. Find it weird that your HV seems to be concerned that you're pregnant unless you've informed them that you've not been using protection. I honestly wouldn't be concerned unless you think you have other pregnancy symptoms. I'm personally enjoying the lack of period for now x
I am almost 12 weeks pp and only just started my period. With my first I had it 4 weeks pp. It varies massively person to person and baby to baby. Its completely normal x
I saw a physio this week who told me that period can come back as early as 6 weeks PP, but average is 9 months.