T-knots are just one of the variants of the TH. They are tough to tie in the beginning and tougher to explain. T.O. has it right about tying it loose. Some TH can be done on the tight side, but some just have to be done loose. Rubber cement is a lifesaver too.
I've done a few T-knots and X-knots, but only in rope. I glean my info from Ashley's Book of Knots. Unfortunately, it's loaned out right now, but we'll see what we can come up with. Hopefully, Brian (Knothead) can join this thread.
Figure 5 shows the back of the knot. Keep referring to this figure after every pass. That's gonna keep you grounded as you move on.
Figure 1 is good.
Figure 2 could possibly be confusing as the string goes around the back without going through the ring. This is where you jump to Figure 5 to see where it is.
Figure 3 has the same action.
These two figures tell me that I need to keep that knot loose for now. Otherwise, I'm gonna be moving those strings (passes) (2 & 3) into positions that they are not supposed to be in.
Figure 4 is just showing you what Fig 3 looks like with string and not an arrow.
Figure 5 is where you see how you've done.
Tightening a TH is just as important and way more time consuming than the first pass. It can take 5 minutes to "build" the first pass and an hour to tighten it all up after 3 passes. If you hurry and make a mistake, it can look like the TH was built incorrectly when it is only a matter of a crossed pass. Also, a rule I've followed for the past 50 years is to "never cut the ends of a TH until I've closely inspected it 3 times for errors.
G'luck and have patience.