The Universe is both infinite and finite.
Don't think of it in 3d space. You cannot build a 3d model of the universe like you can a globe.
The big ban happened everywhere and yet, in a sense, it was very small when it happened, in a way. The universe was created everywhere. There is no middle to the universe and there is no edge. But, yes, it is limited.
Consider this. If you travel on earth in a straight line will you ever reach the end of the earth? Of course not, you will loop back to where you began. Does that mean the earth's surface is infinite? No it is not. Well, yes and no. You can walk forever on it on a straight line. But the surface area is limited.
Space is like that but on a higher level of dimensions. If it were possible to go faster than light and if you traveled in any direction in a straight line, you would end up eventually back to where you started.
It is hard to grasp, I know, but it was once difficult for people to imagine that the world was round.
Just as it is not possible to have an accurate flat map of a globe, it is not possible to have an accurate 3 dimensional map of space and the universe.