Normal for twins or no?

Am

I am 22 weeks and lately my lower abdomen just feels... tight? Heavy? It isn’t necessarily painful and is pretty much a constant feeling when I’m standing. Is this just from the heaviness of having two babies or does this sound like an issue?

I was supposed to have an OB apt last Friday and was going to talk to them about it, but it got canceled due to a labor. Now appointment is this Friday!