HUGS! I've been there. DS1 and ds2 are 15 months apart then ds2 and ds3 are 20 months apart. It's rough being pg with a little one. I felt so guilt when I was pg with ds2 but I just tried to do the best I could. The good part is they won't remember this time. DS1 is a very loving happy little boy at 3 years old and doesn't remmber that I couldn't take him to the zoo or to the park all the time at 13 months old. I did try to do little things like pick some books that we could read from the couch or just sit with him and watch mickey mouse.
All of this! I have two girls, 11 months apart, and one on the way. DD2 and DC3 will be 26 months apart. It is hard, but it is okay. Like Daisy said, they won't remember. They know we love them! Just do the best you can.