i made a post like this years ago w tonnes of great responses, check it out
personally, though, id recommend witchy (trans girl character and possibly gay girls) and les normaux (generally lgbt magical slice of life) and a turn for change (girls romancing girls, butch girls, the works)
theres also my comic, there was a war, in which the two lead characters are lesbians and the main character is, in a sense, nonbinary (its complicated because theyre not human) although i have to warn you, its a tragedy. i hate to bring out a lesbian tragedy in this current climate, but you know when a story just has to get out of you? yeah.
this is also a blog for collecting lgbt webcomics - not all of them will be on tapastic, but a lot will. theres other sites like this but i cant find them rn, but look around!