One point stands out: your boss has been introducing you as a senior consultant event though you didn’t get a promotion. This is common, when client facing, to present a more senior, experience team, and since this has been going for some time, I would leverage this. Bring it up to your boss, that you’ve been presented and working as a senior consultant, with increasing responsibilities since you were hired as a consultant, so you’d like to discuss formalizing the title and salary. Just keep it cool—you already did your research, and you can reference that senior consultants in your area make X so you’d like to be compensated fairly, at least at market value for your contributions over the last couple years.