Here's my suggestion for working out portion sizes:
1. Join a website like http://www.myfitnesspal.com/
(and d/l the app if you have an iPhone)
2. Buy some scales.
3. For a period of (say) 1 week, weigh everything you eat and log it into the site/app.
This will give you information on the protein/carb/fat breakdown of all foods (honestly the amount of stuff they have on there is insane, including all branded items) and also tell you the calories for that amount.
After a week you should be armed with enough information to make informed guesses about what you're eating.
There is a 4 though:
Do not get obsessed with logging everything you eat! That is a downhill path to Crazyland
With regards to eating healthy tasty food:
- Canned beans are good, or cook up a massive batch so you only have to do it once or twice a week.
- Nuts are awesome - peanut butter, almonds, pumpkin seeds etc.
- Buy spices - I put chilli on most things I eat, but also Indian or Mexican spice mixes that you can add to things are good.
- Also things like vinegar and lemon juice for salads
- Marinated grilled meat is a winner.
- So are big stews and thing - cooking big batches (including roasted meats) is much easier, and although you have to eat the same thing for a few days it really saves on brain power having to think about what you're gonna eat next.
Hope that helps a bit.