Jaydess® is a low-dose levonorgestrel intrauterine system (LNG-IUS) that offers women a reliable form of contraception. Jaydess® is an effective long acting contraceptive providing up to 3 years of freedom from contraception routine.
Jaydess® is the smallest IUS available and comes in the smallest placement tube of only 3.8 mm. (2016 Pubmed)
Alternatives:
The traditional rhythm method is recommended in combination with male semen retention in The Tao Of Health, Sex, and Longevity:
A woman is relatively “safe” from conception during the 7 days prior to and immediately following the first day of menstruation. If as an extra margin of safety we reduce that to 5 days, we then have an 11-day period each month during which pregnancy should not occur. During that period, a couple may make love anytime, anyplace, and as often as they wish, with or without male ejaculation, without worrying about pregnancy. This is the traditional rhythm method. (5751-5754)
The book also has some interesting recommendations on herbal birth control
For thousands of years, the young women of Polynesia have enjoyed complete and uninhibited sexual freedom prior to marriage, with no worries about unwanted pregnancy. Their secret is to eat a few handfuls of papaya seeds every day. The active ingredient responsible for their freedom from pregnancy is vitamin B17, more popularly known as laetrile, the controversial drug banned in the United States due to unproven claims that it can prevent and help cure cancer. (4571-4574)
You can't buy laetrile itself (there's bunch of interesting conspiracy theories why) but you can eat foods high in it apple seeds, Californian apricot seeds (eat 6 or 7 seeds), peach seeds and bitter almonds.
Alternative Drugs: Levosert.