Ilovesmepets said:
I was wonderin if there was a way to tell what sex sliders are when they are still young.
Sliders (I'm assuming Red Eared?) cannot be sexed accurately until they are around 2-4 inches in length. The reason for the 2 inches of uncertainty is because you sometimes cannot tell if an apparent female is really just a late bloomer male in disguise.

Females will be naturally bigger full-grown. Males will have very long nails on their front legs and a larger, longer tail.
Ilovesmepets said:
I have two and one is alot bigger than the other one, but they are both healthy and eat the same amount of food.
This is not at all uncommon. Even sliders born from the same clutch and raised under the same conditions will grow at dramatically different rates. As long as they are both eating and active don't worry about size differences.
Ilovesmepets said:
I'm fixin to get them a bigger tank too.
What size?
Ilovesmepets said:
If one is a female, what age do they start producing eggs?
They start producing eggs not long after they reach sexual maturity ... which depends on their size more so than their age. It is important to note that your female (if you have one) will produce eggs irregardless of whether or not she has a mate to fertilize them. You have to be prepared to provide her with a nesting site or she could have problems such egg binding, which you mentioned.
Ilovesmepets said:
I've heard of turtles getting "egg bound". Is this a bad problem?
Yes, it can be deadly to your turtle. Egg binding (called dystocia in reptiles) occurs for a number of reasons. First, it may just be that you have a first time breeder that is having trouble passing eggs ...
They may not be aligned right on the way out ...or there may be an obstruction ...
Other causes are rooted in poor husbandry. Lack of proper humidity, dehydration in the female, lack of a proper nesting site, egg retention due to being kept in improper conditions, temps, diet, and calcium intake are all factors. Conditions really do have to be monitored closely if you have a pregnant turtle to make sure all goes well and you don't have problems.
Ilovesmepets said:
I've contemplated letting them go, but I don't know if I should since I've been feeding them so long. I know I should have let them go to begin with, but my cousin (he's a kid) begged me to keep them. I love these guys and want the best for them...
Why, exactly do you want to let them go? Is it because you don't have the resources to take care of them or because you feel guilty? There are an abundance of RES in the wild so don't feel guilty about taking them from the general population any more than you would for any other exotic pet. Of course, you should always try to buy captive bred turtles but keeping your two RES isn't going to be detrimental.
As to letting them go ... if you have had them for under a year than they should be able to have as much chance for survival in the wild as their peers since they haven't had too long to depend on you for food. However, there is the issue of winter coming ... your turtles haven't had time to build up fat stores for hibernation so if you release them they might not make it. If you do decide to go through with it wait until Spring ...