Chapter 4: The beginning of the Isabeline Era
The news of the liberalization of Spain soon reached Europe and the Americas. Many British (who had contributed to the Isabelline victory), French and German bourgeois were encouraged to move to Spain, which revived a Spanish economy hit by war and needy of industrialization. Meanwhile, the members of the Holy Alliance (Prussia, Austria and Russia) saw as first France, and now Spain, had embraced liberalism. At the other side of the Atlantic, the former Spanish colonies cheered up, as they knew a reactionary Spain would be far more hostile towards them. As for the United States, they didn’t bother to celebrate the liberal victory, but actually took advantage of Spain’s weakness during its civil war.
Chapter 5: Texas
Texas was now independent, and claimed the areas East of the Río Grande, though the young Texan nation was not recognized by Spain and other major powers like Britain and France. The talented criollo Spanish officer, Antonio López de Santa Anna, took de facto the deceased Iturbide’s place as General and Commander of the Royal Army of New Spain, even though he had been defeated in the final stage of the war.
I'm no expert in war matters but this quotes from your TL could help you to write the outcome. TTL Spain, if I didn't read wrong, is "bigger" and something "better" than OTL Spain. Also remember that gold (Perú) and silver (México) can buy a lot of wills (slave revolts in Dixie and Texas, anti-US British and French politicians, British and French colonial troops which "casually" were "over there")...