I'm sorry to hear of your troubles with incompetent floor mechanics. The first thing I have to say, is that the 3 re-sandings of that floor have now removed almost half the life of the wood. On a 3/4" T&G brand new floor there is only 5/16" of wearable (sandable) wood on the top of the groove. And pine being quite soft tends to get sanded quite deeply each time. So the first thing is to check the ends or side of the pine floor boards and see just how much wood is left. Hopefully at least 3/16". Otherwise you should not have the floor sanded again, but chemically stripped, and finished properly. And you might consider having these floor guys compensate you for removing 1/2 the value of this floor. Sorry to be such a rabble rouser, but I speak the truth. Oh, and I do have a most excellent article on just how to chemically strip a wood floor, without removing any more wood. I don't know if you want to go this route but you will find this long and detailed treatise on the Home Page.
But now lets get to how exactly to finish a pine floor, if you really want a waxed finish that you can maintain yourself. It's not a bad idea to do this seeing how pine is a very dent and scratch prone wood, and waxing it yourself once a year is fairly easy to do.
But paste wax (and that is what I'll be discussing here) is not really a wood finish, but merely a top dressing for an already film finished floor. That is because wax by itself will not keep the floor from getting water damaged (from the least little spill) and as you can see, unless the floor is well finished (some say "well sealed"), wax cannot be buffed to the nice satin sheen it is known for. So what would be a good base for pine. Pine is not only a very soft wood (even SYP) but fairly porous and needs multiple coats of some sort of film finish. Although in my opinion 4 coats of satin polyurethane makes the very best finish for a pine floor, there are many alternatives. The most natural (but least water resistant) film finish is shellac. For you purposes at least 5-6 coats of shellac can be brushed or rolled on to a well sanded pine floor. It dries very fast so 2-3 coats can be applied in one day, and is ready ot walk on in 2-3 hours. Shellac is made from the excretions of the Lac bug in India and is picked by hand. It is simply dissolved in alcohol and there is your most natural, least toxic film finish. It's been adorning furniture for 300-400 years in Europe. Let the shellac cure for about a week or two, then give a final buffing and apply a LIQUID FLOOR paste wax, as described in the second half of my cleaning article, found in the Quick Links in this web site.
But the point here is to find a floor mechanic that has some experience in using this very fast drying and flammable finish. It's tricky to use, but dries reliably and seals pine well on the knots. The floor has to very finely sanded, and then the shellac is mixed from it button or flake form. Apply smooth even coats, and screen and clean the floor between coats. If you choose a orange shellac for the first two coats it will give the floor a decided amber color, so no stain would be needed
And that's the trouble with pine, if you do want it darker, staining pine floor is beyond the capabilities of most wood floor mechanics. I just completed today a set of pine stair treads that I GEL stained and will be finishing with 4 coats of a satin poly. It's a tricky job, but the point is only gel type stains will prevent the pine from becoming blotchy. But gel stains HAVE to be coated with poly, not shellac.
The so called "sealers" that these guys used are sealers in name only, and did not give the wood enough film to provide a surface for the wax to build any sheen. The first guys using "fast dry" stain (it has very little binders in it, no film build here), was the most poor choice for pine. Then, the second job with poly was just sloppy, and if done correctly should have come out beautifully. It's roughness would have been corrected by a thorough screening and 2 more coats applied, they way I describe in my "Applying Polyurethane Without the Bubbles". An absolute must read before using this great finish. Oh, and poly once cured for 30 days can be waxed if you wish, no problem.
And the last job with the Dura Seal natural finish ( just a really expensive diluted oil/varnish) might have been OK, but these finishes have to have about 4-5 coats applied and 2 days cure between each coat application, and 30 days of curing before applying wax. You can see why we don't use this stuff.
Water based finishes are not safe, and will give the pine a pale washed out look, so don't let anyone talk you into that. I'm going to send you two pictures. The first is my own Eastern White Pine floor that I sanded and finished about 22 years ago with 4 coats of satin poly. It's dinged and dented, but holding up just fine. The second picture is a the same species GEL stained to give it a more antique look. I'm right in the middle of this job, and will finish the treads with a nice satin poly, no plastic look here.
As always your Most humble servant, Joseph, the Wood Floor Doctor.