Every time you have sex with someone without knowing for sure that they are negative, you are taking a risk. While condoms help reduce the risk, they do not eliminate it completely.
I would not worry too much about your symptoms. Those could be symptoms of many things, not just HIV. In fact, many people do not have symptoms that early. Many people have no symptoms when they test positive. Some have no symptoms for ten years.
Most people will accurately test within three months. In rare cases, it will not show up until six months or more after the encounter. So chances are, if you had a negative test at three months, you are negative. However, testing again at six months would be a good idea just to make sure.