What is a sevenling? A very good question and one which I should have addressed before posting my attempt. A sevenling is a poetic form composed of seven lines with certain specific rules. I just found this description which is much better than the definition I followed in my attempt. As you can see below, I didn't follow the rules exactly ----- oh, well, maybe I'll try again someday.
"Sevenlings by RODDY LUMSDEN
The rules of the sevenling are thus:
The first three lines should contain an element of three - three connected or contrasting statements, or a list of three details, names or possibilities. This can take up all of the three lines or be contained anywhere within them. Then, lines four to six should similarly contain an element of three, connected directly or indirectly or not at all. The seventh line should act as a narrative summary or punchline or as an unusual juxtaposition. There are no set metrical rules, but being such as short form, some rhythm, metre or rhyme is desirable. To give the form a recognisable shape, it should be set out in two stanzas of three lines, with a solitary seventh, last line. Titles are not required. A sevenling should be titled Sevenling followed by the first few words in parentheses The tone of the sevenling should be mysterious, offbeat or disturbing, giving a feeling that only part of the story is being told. The poem should have a certain ambience which invites guesswork from the reader. "