If you "got skinny" I guess that means that you were not always skinny? If so, why not just go back to what you were doing before?
If you don't like pork, beef or peanut butter, just pick some things that you do like. How about boiled skinless chicken breast? If you cook it right it will be very tender and you can put a little olive oil on it as a dressing. You could even put some veggies in the pot and then it will be "chicken soup"!
Who doesn't like fresh home-made (low sodium) chicken soup?
If you're a "finicky" eater, does that mean you don't like vegetables? If you don't think about eating until you're really hungry, that's okay. There's nothing wrong with that. Being "really hungry" can help you to overcome your finickyness. Eat the items first that you like the least (while you're still hungry) and save the best for last.
It may be difficult to gain much muscle. Everyone is different. Some people gain muscle very easy and some don't. It helps to have a good amount of testosterone.
If you don't have the right hormones in your system, the weight you gain might just be fat and it might go somewhere on your body where you don't want it.
In the end, you might decide that if you're healthy you'll be satisfied just to be healthy.
What's your BMI?