Hi dear,
I have understood your history.
The most likely cause of your symptoms could be number of times you had sex with your partner. It could have physically traumatize your vagina and labia.
However, you cannot ignore the possibility of some sexually transmitted infection since you had unprotected sex. Typically,
Gonorrhoea is known to cause burning micturition. This and other associated other infections can cause infection to the glands situated in labia (Bartholin's Glands). His saying that he does not have
STD is not fool proof. You have to get him thoroughly investigated for STD; and now you too have to get yourself investigated for STD.
Also get your urine examined for evidence of any infection and then if indicated submit your urine for culture and sensitivity which will identify the bacteria and the medicine to which they are sensitive.
My sincere advice is not to waste time. Report to the STD specialist. Understand that there are many sexually transmitted infections whose external lesions seem to be healed however, they have gone into the deeper tissues, other organs and blood and may threaten the life.
I hope you will take prompt action.