I think I'm a big girl on a road bike (5'5" and 220). I have several bikes and always prefer the roadie. I am certain I look ridiculous in my lycra shorts or knickers, but I'm comfy and exercising. So, do what makes you feel good!!! It tooks several short rides to get accustomed the road bike, so just keep at it! Here's a pic of me torturing one of my bikes at a Trek Breast Cancer Awareness Ride:
2018 Trek Silque SLR6 - Selle SMP Glider
2018 Specialized Dolce EVO Comp - Selle SMP Glider
2011 Trek Madone 5.2 WSD -Selle SMP Glider
2013 Giant TCX W - Oura 143