Welcome to the Healing Well Wrapped Club! Gritty has given you excellent advice. At 3 weeks you're at the very beginning of your recovery, so swallowing problems are very common.
I don't know if you've come across this link already, but just in case:
It's the link for my recovery journal. You can see what my early recovery was like, and hopefully get some idea of how difficult swallowing can be.
As Gritty said, this will pass over time, and once healed, you'll be back to eating normally.
Here's another link with some information on "mushy food" choices. If you scroll down the document you'll find some recipes for milkshakes as well.
I had the surgery 3 years ago, and I can still remember being where you are in the recovery. I was told by others here that it takes 6 months for the majority of healing to occur, and a full year for the rest. That doesn't mean you'll be having the difficulties you're experiencing for 6 months...but it should indicate how much farther you'll have to go before you get fully healed. 3 weeks is the infancy of your healing process.
If you can surrender to your recovery and follow it where it leads you, it will be much easier. Those who struggle against it have the hardest time. It is what it is.
I can also speak to the food getting stuck...you don't have to panic when that happens. If you can stay calm, you'll likely be able to get whatever it is down, by taking sips of water or warm tea. (Did anyone tell you to stay away from iced drinks? They can cause esophageal spasms. Stick to room-temperature water for the time being.)
As Gritty said, if you're eating solid foods, you'll want to make sure to take tiny bites and chew, chew, chew until it's liquified. Then there will be nothing to stick.
Again, glad you've joined us! I'm sure others will be by to weigh in soon!