Your shampoo bar is a synthetic detergent; as you guessed, it is not lye-based soap. Nothing wrong with that -- I learned the hard way that lye-based soap does horrid things to my hair. I went back to commercial shampoo for awhile, and am just now starting to experiment with making my own syndet shampoo bars.
Dahlia is right -- Susan (swift crafty monkey) is the go-to girl for this information; pretty much all I know is from Susan and advice given here on SMF and "The Dish," another soap making forum. There are others on SMF besides Dahlia who have made this type of shampoo bar for a long time with good results. I'm a beginner, but will share what I've learned.
SCS is a fairly strong cleanser, so you might find it to be drying to your scalp and hair. Some people don't, but many do. I learned to avoid it when buying commercial shampoos -- it makes my hair feel dry and scalp itchy -- but my DH doesn't mind it at all.
For my shampoo bar recipe, I'm avoiding SCS entirely and am using these solid syndets instead -- SCI (sodium cocoyl isethionate) and SLSa (sdium lauryl sulfoacetate). These are both anionic syndets. SCI is mild with creamy foam. SLSa might be a bit stronger of a cleanser from what I gather, but it makes lots of fluffy, long lasting bubbles. I might experiment next time with just using the SCI as my only solid syndet and see what I think.
Susan says mixing syndets of different types (anionic, cationic, amphoteric) causes the resulting mix to be milder, so I added liquid coamidopropyl betaine to my recipe, again following what I learned from her. It's an "amphoteric" syndet that reduces static in hair and makes a quick foamy lather. It is a poor cleanser however -- that's fine for babies, but not so much for adult shampoo. You need a bit of liquid to create the shampoo bar, so this syndet does double duty as the liquid in the recipe.
I can't speak to the use of lemon juice in a syndet shampoo. If used specifically to adjust the pH to a desired range, it might be fine, but if it's been added "just because" lemon juice is supposed to be good for hair, then I'm not so sure. It might be better to use the lemon juice as a rinse after shampooing and use a non-acidic liquid to aid in making the shampoo bar. But that's just a guess on my part.
