You can contract hsv2 orally but the risk is on the low side. To greatly simplify it- hsv2 doesn't "like" the oral area. Only about 3% of all oral herpes infections ar edue to hsv2. If you aren't sur eof your partner's status, only perform oral over a condom
Please ask your partner to get tested as well. If he is seeing you on and off, chances are he's been sexually active with other partners during the "off" times. Please read up and protect yourself.