Some people are only sexually attracted to people when there is already an emotional connection - either friendship or a romantic relationship. Do you think this could be you?
If that is the case then internet dating may not be your best bet anyway. How about social events and clubs around an interest - singles' walking clubs, or just local walking clubs, volunteering for an environmental/local charity or something (where you get to spend the weekend repairing footpaths, or repainting the village hall). Activity holidays that welcome single people (or are even just for single people).
What are your interests? Do you (did you) play an instrument, can you sing even a little? What other skills do you have that could open doors to a wider community of people to meet?
Activity-based meeting people may also help because both you and other people have the chance to get to know each other's personality, rather than making a snap decision based on looks and swiping an app.
Most people (women especially I suspect) over-estimate both their ugliness and their size. In any case, even if you genuinely would be considered 'ugly' by the general population, it's still subjective. There's some psychological research which suggests people are attracted to those of 'matching' desirability in terms of looks (though age, social skills and factors such as wealth can lead people to adjust their rating). Therefore there will be people out there who will be attracted to you (and possibly you to them), it's just they may not be classically good-looking. Does it really matter, as long as you find something attractive in them, and they in you?
Personally I am usually only attracted to people who I know quite well. (Though for the odd celebrity I fancy it will be due to a blending of intelligence, humour and looks, rather than just looks.) As long as I find the person funny and intelligent, and there is something in the person physically that makes me swoon (not the whole package, just one thing is necessary - like nice hands, or eyes), then I will end up finding them attractive as a package. Do you actually know what you find attractive about someone?