The fertility awareness method (maybe using natural cycles) could be suitable for your needs. ONLY use this method if you have an extremely regular menstrual cycle. ONLY use this method if you don’t mind getting pregnant sooner than you plan. You would have to track both your basal body temperature and your cervical mucus to use this method effectively.
Spermicide on its own has around a 20% failure rate, so is not recommended for use on its own.
Additionally, I would not recommend the spermicide you named as it contains nonoxinol-9, which can upset the natural bacteria in your vagina (which increases your susceptibility to thrush and Bacterial Vaginosis), can cause vaginal lesions, and has been linked to a higher rate of vaginal and cervical cancer.
If you want to use spermicide, it is more effective when combined with a diaphragm or cervical cap. Examples of nonoxinol-9 free spermicides are Caya Contraceptive Gel and Contragel Green.
The Copper IUD is another option. It has no hormones, and so does not disrupt you natural menstrual cycle. Copper is toxic to eggs and sperm, and creates a foreign body reaction in the uterus, meaning that if an egg manages to get fertilised, it cannot implant in the uterine lining. Depending on the model, they can last 5-10 years, but can be removed at any point and do not affect your natural fertility.
Skyla and Kyleena IUD’s, which a pp mentioned, are not hormone free, but are good low-hormone options.
Lastly, condoms or femidoms are effective options. If your partner is resistnant to using condoms due to reduced sensation, they may prefer femidoms.
It would be a good idea to consult a sexual health specialist (advisor, nurse or doctor) as GP’s tend only to have basic knowledge of the options, as they have to know a little about a lot, and usually give very generic advice when it comes to sexual health, unless they have a specialist qualification for this.