Eating out does not equal eating at home. I bet you eat a lot healthier at home than you do in a restaurant. Just because it's not fried doesn't mean it's not overly fattening. Fat bothers a lot of people with IBS, especially those people post-gall bladder. Restaurants often cook in canola oil and butter and use a lot of extra sugar (which isn't fattening, but not good for you either). Any steak but a filet mignon is way too fattening (and they serve too many ounces of it to boot). You may want to start checking the fat content of things before you go out. A lot of chain restaurants put their menus and nutrition information online. Those who offer a healthy section on the menu tend to have fat and calories listed on there as well. If in doubt, ask. If I remember correctly, federal law requires content information to be available. Too many people with deadly food allergies.
Also, examine what you drink. Do you drink more caffienated drinks when you eat out than you do at home? Do you drink alcohol when you go out? Both can be harmful to IBSers. Even if a coke doesn't bother you at home, a normal restaurant glass holds half as much again or even twice as much as a regular can of coke. And a lot people drink more than one glass because it's a "better value" because refills are free.
Sometimes it's not what we eat or drink but how much we consume at one time and how frequently. I'll go through phases where one coke won't bother me, but if I ever drink more than one can, it's to the toilet for me. Half a frozen pizza is fine, but a whole one makes me sick. Pizza too many nights in a row can cause problems as well. Also, dbab is right on about smaller portions; retaurants have, for the most part, doubled the amount of food you get now as opposed to 10-20 years ago. And studies show that if you see it on your plate, you will eat more of it. Everybody does this, regardless of sex, age or nationality! Speaking of steaks, do you know your recommended portion of meat is only supposed to be about 6oz? Compare that with a 12oz T-bone. Compare that to a half-pound (8oz) restaurant burger--or, God help us--one of those 1 pound burgers (16oz) from a fast food place. You may want to try getting a to-go box along with your meal and immediately dumping half of it (or more) into the box. This way you will eat less, hopefully get less sick (or not at all) and if you wind up hungry in an hour, you still have food to eat. And don't forget that ice cream is WAY full of fat and that a serving is only 1/2 cup (one scoop--not running over).
And you might want to eliminate the salads. A lot of people here have trouble with raw vegetables. Not to mention that some pre-cut lettuces--especially those on open salad bars--are "washed" with bleach and/or other chemicals to keep it from browning too quickly. If salads at home are fine but salads out are bothering you, the lettuce may be the culprit. Before I even started having IBS/ gall bladder problems, my college's salad bar gave me diarrhea. Salads at home don't bother me, but I always use a whole head of lettuce at home and cut it up myself; I never get the bag-o-salad things.
You certainly may be causing your own problems by worrying yourself into them. I know I almost always get sick before we go on a long road trip. I don't know why, but I do. Short trips don't bother me, nor does eating out. I do medieval reenacting and we frequently travel an hour or more to go to an event, but I'm not bothered by that. My family is an hour and a half away, but I never get sick just because I'm leaving to go see them. But 3 hours going to my in-laws messes me up. Going on a regular vacation messes me up. I have no idea why. I don't think I feel more anxious. Lord knows my m-i-l can sympathize if I go to her house and hole-up in the bathroom; she has IBS too. Some workings of the gut just can't be explained. I've just learned to recognize oncoming symptoms and adjust my medicine accordingly.