Being grateful does NOT mean being content. If we were to remain content with everything there would be no point of making dua and asking for things. Allah wouldnt have commanded us to make dua during times of ease if we were to remain content with what we have. Being grateful just means to acknowledge what Allah has already given us, reflect on them and praise and thank Him for them. It does not mean we settle. In fact Allah commands us to pursue a life of excellence and ask for His bounty. Allah says in the Quran in Surah Rum that seeking His bounty is actually one of His signs. So yes, sometimes you will feel grateful but also simultaneously you will feel what you have is not enough, it just doesnt cut it. Thats okay, Allah said to be grateful for things He has already given you, and thats it. Human beings taught you to settle, not Allah. So dont confuse it.
Also, if dont guilt trip yourself to feel grateful. Its good to look at people who are less privileged than you and reflect on your blessings, but its a whole different story altogether to just not ask for anymore because “you already have so much” or do just feel guilty that you are so blessed.
One last thing, dont fight yourself to feel the gratitude rush all the time. When Prophet Yaqoob lost his youngest son, Allah didnt tell him to be grateful for the other ten. Allah allowed him to whine and complain like nobody’s business, and even recorded it for you and I to take inspiration from.