Squashed into a tent with six other families in Tundikhel park, in the heart of Nepal's capital Kathmandu, Anhita Pahari worries about her young son Suman being safe.

“It's suffocating and hot inside, already people are feeling feverish,” she said, soaping clothes in a bucket near the tent's entrance. “At night, people try to come into the tent to rob us.”

Three weeks ago, Pahari leapt from the second-story window of her apartment as it collapsed when a 7.8 magnitude earthquake rocked the landlocked former Himalayan Kingdom.

The worst earthquake to hit Nepal in over 80 years left the capital in ruptured chaos. It was followed by a string of aftershocks including one of 7.3 magnitude on May 12, which killed at least 117 people and injured 2,682, bringing the total death toll from both disasters to near 8,500 with tens of thousands injured. The numbers are expected to climb with many thought to still be buried under the rubble.

The quake wrecked more than half a million houses, leaving hundreds of thousands like Pahari and her 10-year-old homeless. Monsoon rains are due to lash Nepal for over two months starting late May, with rebuilding expected to begin after the skies clear. But more than weathering this under a flimsy layer of tarpaulin, many of Nepal's new homeless fear for their safety.

Aid workers are equally concerned, hearing reports of sexual violence, crime, and caste discrimination in formal camps and makeshift shelter clusters. Devanna de la Puente, a protection advisor for the United Nations Populations Fund, said opportunistic attacks are known to spike during disasters when people lose their homes and support networks. Most at risk are single mothers and Nepal's many marginalised castes and ethnic groups.

NGOs are trying to provide support but haven't reached everywhere, particularly the most isolated villages near the China border. They're only accessible by hiking hours uphill, and when monsoon rains hit they get cut off entirely. “We know that we don't have a presence everywhere,” de la Puente said. And the second quake put aid workers further behind. With more affected areas needing help, de la Puenta said.

Complicating matters, aid agencies don't have a clear view of how many are out of home, particularly in rural areas where populations scatter across mountainous terrain. “It's very difficult at this point to say how many are actually physically outside, we don't have those figures,” said Jamie McGoldrick, the United Nations Humanitarian Coordinator in Nepal.

The trembling left many of Nepal's vertiginous terraced hillsides laced with cracks, including those in Dolakha District, the epicenter of the second quake. There the urgent need is not to build makeshift shelters but relocate people fast, according to Tibendra Banskota, Plan International Disaster Relief Coordinator. “There is no appropriate place to rebuild houses,” Bonskota said. If people aren't provided new land, “monsoon will start another disaster,” as cracked sections sluice away in landslides.

Meanwhile, many across Nepal remain angry with the government, which was criticized for not acting fast enough to provide relief. There are claims too that some of the assistance it did promise has not been received.

After admitting it was too slow to respond after the first earthquake, with Interior Minister Bam Dev Gautam saying authorities were "not prepared”, the government swung into action. There were announcements of billion dollar funds for relief and rehabilitation, compensation for families of the deceased and those who lost their homes, and free hospital treatment for the injured.

But patients and visitors in Bir government hospital, including Amrita Magar, say treatment has been far from free. “We had to pay for the X-rays and bandages,” she said, rearranging a blanket on her 11-year-old brother Anoj to cover his plastered left arm. The young boy tripped fleeing as their house crumbled in the first earthquake. “I thought there would be more from the government,” Magar said.

The hospital's director Dr Swyam Prakash Pandit is also yet to see any money to compensate for the “free care,” he said was provided to more than 1500 victims. “Till now we have not got it,” Dr Pandit said, adding that he believed it would come eventually. Red tape has been widely blamed for slowing down aid. That entangling supplies at Nepal's only international airport in Kathmandu was cut away after the UN called for custom restrictions to be eased.

Meanwhile, those homeless are resigned to helping themselves. “The government didn't help us when we needed it,” said Krishna Bahadur Khadka, who travelled to Kathmandu after his house collapsed in Dolakha and now sleeps in a tent with seven families. “We now realize they're just a bunch of dakas [Nepali for gangsters].”

Pahari pooled her money with those in her tent to buy mats to cover the grass and food to supplement the small packets of noodles and biscuits they each get a day. “We've been looking for accommodation but people have stopped renting rooms,” she said. “It's hard to find anywhere.”

The UN is focusing on pushing supplies into isolated areas in the 14 worst affected districts before the monsoon season hits – flying it in by helicopter, sending teams to distribute on foot, and thinking about using mountaineering porters. As McGoldrick said, “this is a race against time.”