My car keeps overheating it don't leak or anything it just keeps overheating? I cant drive for very long distances, and also I already changed the thermostat twice, what is the problem?

Try bleeding air from system like this remove cap from overflow tank fill with antifreeze to full mark leave cap off and start vehicle and let idle you will notice level in tank start to rise this is normal once thermostat starts to open level in tank will drop add more antifreeze to full mark then put cap back on

It may not be leaking YET, but if you continue driving without getting the problem fixed it eventually WILL LEAK when the undiagnosed problem reaches its "boiling point". Although it is tempting to deny that your vehicle has a mechanical problem requiring immediate service, something is about to "burst" (such as the coolant overflow bottle due to, perhaps, the cooling fan motor going "bad" but has not quite reached its threshold). I recommend that you take your vehicle to a service garage ASAP ... unless you like surprises and you'd rather break down on the road at a time and location that will undoubtedly be quite inconvenient to you!

Sounds like your cooling system needs some TLC. If you have replaced the thermostat you need to look at the other functional parts of the system. Your radiator my be clogged (either internally or blocked by dirt, damage, or bugs externally) and not getting sufficient air flow through it to bring the coolant temp down. Also, your water pump may not be pushing fluid rapidly enough through the engine due to age and deterioration. A failing radiator cap may also contribute to the condition by not releasing at the prescribed pressure. Look into these things if "bleeding" does not solve your problem.