Oh Well I'm A Bit Embarrassed To Write This But

Oh well I'm a bit embarrassed to write this but I've tried very thing basically I can't find my vigina opening nor see it I've did a lot of research and tried many times to try I went to the doctors but she said I was completely fine I mean I get my period every 5 weeks so there must be a hole right? Me and my boyfriend of two years have decided we were ready to start being sexsully active but this is stopping us I'm completely ready and I am relax when we do anything I've even tried to do it alone but it's like a lump where the opening should be and it feels like a wall stopping me from pushing my finger any further please help I'm on a swim team and I need to use tampons soon as well