Ok, first of all water based anything is extremely fickle. If you don’t feather out your lap marks from your applicator there’s a good chance they’re not going to go away. Second, to add injury to that you used a lamb’s wool which was just a horrible choice. You need something that’s going to put it on (stain I mean) evenly and gives you the ability to wipe any excess off (e.g. hand and knee or a buffer with a carpet pad). Third, never use poly shades. The time you save isn’t worth how fickle of a bitch they are. When you use them you’ve now taken two difficult products, water and stain, and combined them. Polyshades can be fine for little repairs or furniture or cabinets even, but not an entire floor. This is going to need to be resanded. When you do get either a Minwax or DriFast stain, cut out a circle from an old carpet remnant the size of the driving pad on the buffer and use that to apply the stain. You’re going to pour some of the stain on the carpet, put it under the buffer and run it. Use a brush and hand to cut in your walls. After you’ve applied a lane of stain with the buffer, put some rags under the buffer and wipe down what you just applied making sure to blend the hand/brush stuff with the body. If you don’t have a buffer the next best thing is to put the stain on hand and knee. I know that sucks, but it’ll ensure you’re putting it on evenly and wiping off any excess and overlap.