Should I go see a psychiatrist?

For the past few months, I've been experiencing really disturbing intrusive thoughts and obsessions. I just turned 18, and I've been thinking of going to see a psychiatrist for awhile now. I have an insurance plan that would cover the costs. The problem is my mom, who is a nurse, is worried that if I were to go to psychiatrist and get diagnosed with something such as OCD or GAD that I may have trouble getting insurance in the future. She is worried that it would be considered a preexisting condition and I wouldn't be able to get an insurance plan after I turn 26. She even suggested that we pay out of pocket so it wouldn't go on the insurance, but I think the price would be astronomically high. Is this likely to happen? I think seeing a professional would do me a lot of good, but I don't won't to screw myself over for the future.