Sudden-dramatic drop in milk supply 7 mo pp

Arin
I'm 7 months pp and about a week or so ago I noticed a dramitic drop in my supply. We did introduce solids a few weeks ago but I nurse before and after so I can't imagine it would affect it that much. I still haven't started my period so I thought I might be staring but haven't yet. I mainly nurse but we went on a road trip last weekend and I was only able to express 1 ounce with my hand pump each attempt! It was shocking! 
I've been trying the typical supply boosters and nothing seems to by working so far. Help!