I'm woried my penis has shrunk, is this possible?

hello, I'm a 20 year old man, I'm not sexually active I've been with 2 woman only those 2 times. 3 weeks ago I measured my penis by lack of confidence I guess, since I didn't have a ruler I measured it with an online ruler by drawing the measures on a piece of paper it turns out I was only 5 inch long so then I went out to buy an official ruler per say, it turned out I was measuring it wrong, the measures on the paper were longer than the ruler, I was a little over 5.5 inches puting the ruler beside the paper. Since then I started getting really nervous and wanted to get the official measurement with the actual ruler. Now everytime I measure I get nervous and anxious, my penis lenght now varies from 4.5 inch to 5,(not fully erect) I can tell because I remember I could put both my hands in my penis and the top would show up, now it does not! I'm woried my penis has shrunk, is this possible? Cam a viagra pill help? Btw I'm only 2.5 inch flaccid. Answer honestly and objectevily please.