No Crusades. The First Crusade especially helped turn the tide in favor of the Romans for a while.
Let's try this on for size, with a PoD of No Crusades from the 1090s related to a period of lethargic Popes in Europe, and continued Seljuk waxing, even into Europe.
Blue represents the OTL history of Ottoman expansion and beginnings of contraction in Europe. Now, in this ATL situation of continued Turkish momentum through the 12th century (and beyond) it would not and could not match the Ottoman schedule exactly, which is what is represented in red. I could only just squeeze in the fall of Constantinople before 1200. But, I figure this gives a rough estimation of when the Turks could conceivably build from one conquest to the next, give or take some years.
So the idea is the Seljuks first make it across Gallipolli in 1101 and take Constantinople in 1199. From there I project in red Seljuk expansion.
Green represents other OTL events, not related to the the Turks, of significance, like the Mongol invasions and the Black Death.
Conceivably, the timing of the Mongol invasion of Central Europe could soften up the Hungarians enough so that Turks established in the Balkans could exploit this and conquer them.
An interesting facet is that the Golden Horde is already set up and influencing Eastern Europe, and, I forgot to add, converts to Islam in 1313.
And Lithuania is still pagan at this time.
Perhaps in this TL, after the Black Death strikes, the early Turks, or at least Islam, get further into Europe. For example, Poland was smaller, weaker and fragmented for a lot of the 1200s and early 1300s, and Lithuania might convert to Islam and ally with the Turks and the Horde.