I think you need to check thermostate valve again by putting it in bioling water to see valve is opening properly or not. This is dangerous and also check radiator cap for perfect sealing ............ some time i can not resist against pressure inside radiator and leaking gas
best of luck keep an eye on temprature needle and keep checking water level in radiator and resorvior every day untill ur satisfied specially when u go on long drive and keep 3 4 pepsi water filled bottle in case of leakage ...............
In case of emergancy and leakage in radiator ............. u can keep black peppar (KALI MIRCH) one table spoon in radiator to slow down leakage for some time temperary solution but can give u time to reach mechanic for repair............ share with friends as well can save them from hell mess some day ............. 2 3 egs can also work to stop leakage in radiator.