When I first started HRT I found I couldn't reach my big O for roughly six months, every time I came close to the O it did a runner on me. I think it was because it was quite different from the O I'd lived with for decades and my brain was so shocked that it jolted me out of the zone.
Once I passed that hurdle it became easy, trust me.
If you're not comfortable with toys then try this method, I wear contouring underwear which keeps everything in place and prevents me from feeling what I have down there. I use both hands to jiggle the tip through the fabric and have reached O in less than 5 min that way.
Its hard to describe the motion I use so have fun experimenting with different pressure/direction etc.
Also, don't let it stress you as that's counter productive