Lots of sound advice here, son. Listen to it all. Most importantly, if you're serious about a career in this field, a minimum of a Masters is required these days, if not a Ph.D.. I got my B.S. in 1987 with my goals set on law enforcement. During college, I worked for a private group studying raptors, specifically great horned owls. In 1986, I was the youngest presenter at the Raptor Research Foundation Conference in Florida. It was there that I was offered a sponsorship to McGill University in Canada. I didn't go. Looking back, I should have decided otherwise. But, I've worked a number of interesting careers in my life and now am an employee of the federal government. I get 11 holidays a year, five weeks of vacation, and am in the 90th percentile of per capita incomes in my community, so I'm taking care of my family well. After school I interviewed for an Agent's position with the state of Missouri and was 1 of 250 people interviewing for 12 jobs. There were over 2500 applicants. I don't think the field is any less crowded today as it was back then. Sounds like the professors are still giving the same negative advice. LOL
If I could give you one piece of advice today, it would be to make the effort to meet as many people in the field as you can. Better yet, make sure they know you and your name. Despite what others will tell you, success is about a fourth WHAT you know, a fourth WHO you know, and at least HALF who knows YOU. When an opportunity opens somewhere out there, you need to have shaken enough hands and impressed enough people that one of them will think of you as the perfect person to fill that vacancy. Someone you meet in the next five years who you think is just a passing acquaintance will someday have an astronomical impact on your life.