I suggest you to use protection, if you 2 loves each other, get tested and start a good relationship, as I had many bad days of anxiety I suggest you to lower any risk as possible.
Isle39 is correct, that there are theoretical risks associated with oral sex, but the risk of transmission is low enough that you shouldn't really worry about it. The two big risks for oral sex are gonorrhea or NGU (although there is a debate about whether or not NGU counts as an STI or not). And, even with gonorrhea, most people don't have it, and most oral encounters, even with someone who does, don't transmit it. There is a risk for syphilis and herpes, but unless your partner has an obvious sore on her mouth, you really have nothing to worry about. So, in summary, oral sex isn't 100% safe, but it's safe enough that you should be able to engage in the activities you describe without too much worry.
As a good rule of thumb, if you're sexually active, you should be getting include an STI screening with your annual check-up. Other than that, if you're only engaging in oral sex, you shouldn't need any additional testing unless you're showing symptoms (discharge, burning while urinating, or lesions/sores on your penis).
The risks of unprotected oral sex are oral gonorrhea, syphilis, oral herpes and oral hpv. Syphilis is a very dangerous disease that has to be treated with antibiotics. Herpes and hpv are for life. Some types of hpv can cause oral warts, others can lead to cancers of the mouth and throat.