I think starting with the SP dietary plans is a good place to begin. They have several options for various health conditions and goals.
The first step, no matter what other plan you choose, is to get a printed copy from your healthcare provider listing the specific things s/he does or does not intend for you to eat! No sense paying for healthcare if you don't use it, after all.
Your choices seem limited to you now because they're unaccustomed. You need to have a reorientation in your mind regarding food. That will be the first hurdle. It's not so bad as you think! The foods you mentioned so far as can or can't seem like good choices, for the most part.
Trans fats are just plain evil for any of us. Throw the margarine out! ;-) Sugars are troublesome for a variety of reasons, and (along those lines) carbs are simply complex sugars. So carbs and sugars should be on a limited list. But you can have plenty of meats, good fats, lots of veggies (I don't think you can overdo it with veggies, so long as they're not all the starchy sorts!). Try to get whole foods - not the prepackaged processed stuff. I don't remember if you mentioned dairy, but if you can have that, real butter and whole milk and eggs are still good things on the menu.
Right now you're reeling from the can't-haves. You're mourning the loss of your favorite foods, and comfort foods as you've known them. But you have a goal. You want health, you want to be there to watch your granddaughter grow. Once you adjust to this dietary change, it will become second nature. You will probably always have fond memories of your old way of eating, but you will find a new comfort and enjoyment in this new plan.
Don't focus on the can'ts. Think of the adventure of learning to enjoy new foods. And this isn't to say you can never have any of those things you've always eaten. There will be an adjustment period when you should probably stay away from them so your body doesn't continue to beg for them. Then, once you've got the new plan in place, indulge yourself occasionally with old favorites. Learn to make old favorites in new ways. Don't shut the door on your pleasures, because you won't be able to stick to the new plan if you do. Remind yourself this is a CHOICE. You can choose to allow yourself a treat occasionally. Or...you could *choose* to fight it and never reach the goals you've set for yourself.
It's really all up to each of us, right?