First off, you should retain an attorney and ask that attorney all of these same questions. This is non-negotiable. You will want this moving forward.
If the contract for this transaction is sound (refer to the "Get An Attorney" section) then you are buying 3% of the company at $3.34mm valuation and, if the seed money comes through at the amount and percentage you state, you have 6x'ed your investment. That's not a bad deal. However, there are some caveats. It all smells fishy.
First, this company has been in business for 3 years or so and they have not seen a profit until last month? Their valuation is effectively $0, especially if they are in the consulting space and not the product space. They have no assets. They make no money. They have essentially no history of being successful. I am not suggesting that they have no hope of becoming successful, just that they currently should not be valued at $3.34MM. That would be 13 times annual gross? No way.
Second, we can extrapolate that they are not worth $20MM. You mention that they were cash positive last month for the first time. Let's say that means they made $35k on a $30k burn. Let's also say they can keep at that level, month over month. At a $20MM valuation they are being valued at 47 times annual gross? No way. The investment firm will learn this quickly as they do their due diligence.
Third, let's look at debt. They aren't paying you. How many other 1099 contractors, vendors, and others are they behind payments on? Do they account that debt and those payments into their $30k monthly burn? I will not speculate, but if you are planning to invest $100k into them, you should know for sure.
If you were going to invest $100k into a company like this, I would suggest a much lower valuation. I would also suggest that you get a board spot. I would not be shy about asking for a stepped up equity position under various circumstances (The other investor doesn't come through? More equity for you. You spend more time working for the company? More equity for you. etc). Say 10% equity for $100k. another 10% if the seed money doesn't come through. X% annually as you help them grow the business over the next 4 years.
Now, if it were me, I would never invest in this deal. $100k is enough to invest in my own successful business without the baggage. I would leave, invest in my own company, and sue them for my unpaid work. But, that's just me.