Am I having a heart problem or PTSD?

Hello doctor,

I have already talked to my very own Cardiologist but have not really gotten much. They just told me I have been having a lot of tachycardia lately but with a normal rhythm. They told me I should be fine but I feel I am not. Three months back, I had gone into cardiac arrest due to a drug overdose when I got a laced pill full of Fentanyl when I tried to get the old medication I was once prescribed, Adderall. It took 12 mg of Naloxone to bring me back to life. Then about six months ago I had an ER visit because I decided to take what I thought was MDMA with some friends for a party. I do not take drugs anymore. The drug test only came back for Amphetamine and I took around 200 mg of the drug Methamphetamine. I started to go into cardiac arrest again but was luckily brought back to normal levels. It was a scary experience which haunts me now causing anxiety whenever I notice my heart rate go up. Three months ago I started to display worse symptoms. My cardiologist only put me on a heart monitor for three weeks but said I had a lot of tachycardia with a normal rhythm. I am not quite sure whether it is just anxiety or if my heart may actually have problems. I am only 18 but I feel these close calls might have put a toll on my heart. I just need somewhat of an answer on whether these experiences could have caused one term problems to my heart at my age. I do not do any drugs anymore. I vape but that is all. I get chest pains through the day and sometimes will get light headed and cannot think clearly. I will space out and not pay attention to anything else around me. I am worried it is a heart problem or could be PTSD cause from those events. Any information will help.