I can not provide a direct answer to your equity question without knowing more details of your total arrangement and those details should already be understood by your lawyer, who would be well versed in the usual arrangements of such agreements. I will say that on the face of it, I think you are making out quite well. Remember that liability is also a concern and with a low percentage of equity I would imagine your liability is limited as well. While you are putting in the hours and providing sweat equity, you are also getting paid immediately and 90K is nothing to sneeze at plus the profit sharing (and we are assuming there are or will be profits). Does the equity increase over time? How is the remaining equity distributed among the investors?
Should the enterprise go out of business after two years, you will have gained 180K in salary from the business. How much of their investment will the others have made back? With 3 percent equity, how much of the business loss will you be expected to suffer?
Then there are intangibles, such as being left alone. If you are the operating partner, how does decision making occur? Do you put up with meddling investors who have money but no experience but still wish to influence daily operations? What is the review process for your performance to insure you are not hurting the others' investments? What guarantee do the investors have that you will not walk away? Should you do so, what recourse do they have?
These are, of course, purely rhetorical questions but answering those questions for yourself should help you gain a better perspective on how much equity is appropriate for your situation.