Yeast Infection or STI?

Hi, I've never had either or before and I know that I need to see a doctor before becoming sexually active again but I'm just trying to get a feel for what to expect.

I started a birth control implant and the guy I was with guilted me into not using a condom (basically said he was clean and if I'm clean and the implant is 99.9% effective there's nothing to worry about) and yeah I know it was dumb on my part but it happened so whatever. I understand that a lot of STDs and STIs are asymptomatic and he could've caught something and not realized. But I trusted him because he was the first guy I was really properly intimate with. But almost immediately afterwards I noticed there was a change in smell down there and I don't know that it's necessarily fishy but it's definitely not normal. I get pale yellow discharge regularly and sometimes it's a thick white discharge. Everything I'm googling (bad I know) says some symptoms line up with a yeast infection some line up with bv. Theres no burning sensation, no sores, but sometimes it itches like if he would finger me without really waiting until I was lubricated enough for it to feel good. I genuinely can't tell what it could be. I want to get tested but I'm on my mother's insurance and I don't really know how that works because I just don't want her finding out I made a stupid mistake. I may try to go to the women's clinic on my university campus and see what my options are there. I'm just really scared and stupid.